Side effects of valtrex



The following serious adverse reactions are discussed in greater detail in other sections of the labeling:

  • Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndrome .
  • Acute Renal Failure .
  • Central Nervous System Effects .

The most common adverse reactions reported in at least 1 indication by greater than 10% of adult subjects treated with VALTREX and observed more frequently with VALTREX compared to placebo are headache, nausea, and abdominal pain. The only adverse reaction reported in greater than 10% of pediatric subjects aged less than 18 years was headache.

Clinical Trials Experience In Adult Subjects

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Cold Sores (Herpes Labialis)

In clinical trials for the treatment of cold sores, the adverse reactions reported by subjects receiving VALTREX 2 grams twice daily (n = 609) or placebo (n = 609) for 1 day, respectively, included headache (14%, 10%) and dizziness (2%, 1%). The frequencies of abnormal ALT (greater than 2 x ULN) were 1.8% for subjects receiving VALTREX compared with 0.8% for placebo. Other laboratory abnormalities (hemoglobin, white blood cells, alkaline phosphatase, and serum creatinine) occurred with similar frequencies in the 2 groups.

Genital Herpes

Initial Episode: In a clinical trial for the treatment of initial episodes of genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving VALTREX 1 gram twice daily for 10 days (n = 318) or oral acyclovir 200 mg 5 times daily for 10 days (n = 318), respectively, included headache (13%, 10%) and nausea (6%, 6%). For the incidence of laboratory abnormalities see Table 2.

Recurrent Episodes: In 3 clinical trials for the episodic treatment of recurrent genital herpes, the adverse reactions reported by greater than or equal to 5% of subjects receiving VALTREX 500 mg twice daily for 3 days (n = 402), VALTREX 500 mg twice daily for 5 days  (n = 1,136) or placebo (n = 259), respectively, included headache (16%, 11%, 14%) and nausea (5%, 4%, 5%). For the incidence of laboratory abnormalities see Table 2.

Herpes Zoster

Table 2: Incidence (%) of Laboratory Abnormalities in Herpes Zoster and Genital Herpes Trial Populations

Clinical Trials Experience In Pediatric Subjects

The safety profile of VALTREX has been studied in 177 pediatric subjects aged 1 month to less than 18 years. Sixty-five of these pediatric subjects, aged 12 to less than 18 years, received oral caplets for 1 to 2 days for treatment of cold sores. The remaining 112 pediatric subjects, aged 1 month to less than 12 years, participated in 3 pharmacokinetic and safety trials and received valacyclovir oral suspension. Fifty-one of these 112 pediatric subjects received oral suspension for 3 to 6 days. The frequency, intensity, and nature of clinical adverse reactions and laboratory abnormalities were similar to those seen in adults.

Pediatric Subjects Aged 12 To Less Than 18 Years (Cold Sores)

In clinical trials for the treatment of cold sores, the adverse reactions reported by adolescent subjects receiving VALTREX 2 grams twice daily for 1 day, or VALTREX 2 grams twice daily for 1 day followed by 1 gram twice daily for 1 day (n = 65, across both dosing groups), or placebo (n = 30), respectively, included headache (17%, 3%) and nausea (8%, 0%).

Pediatric Subjects Aged 1 Month To Less Than 12 Years

Adverse events reported in more than 1 subject across the 3 pharmacokinetic and safety trials in children aged 1 month to less than 12 years were diarrhea (5%), pyrexia (4%), dehydration (2%), herpes simplex (2%), and rhinorrhea (2%). No clinically meaningful changes in laboratory values were observed.

Postmarketing Experience

In addition to adverse events reported from clinical trials, the following events have been identified during postmarketing use of VALTREX. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to VALTREX.

General: Facial edema, hypertension, tachycardia.

Allergic: Acute hypersensitivity reactions including anaphylaxis, angioedema, dyspnea, pruritus, rash, and urticaria .

CNS Symptoms: Aggressive behavior; agitation; ataxia; coma; confusion; decreased consciousness; dysarthria; encephalopathy; mania; and psychosis, including auditory and visual hallucinations, seizures, tremors .

Eye: Visual abnormalities.

Gastrointestinal: Diarrhea.

Hepatobiliary Tract and Pancreas: Liver enzyme abnormalities, hepatitis.

Renal: Renal failure, renal pain (may be associated with renal failure) .

Hematologic: Thrombocytopenia, aplastic anemia, leukocytoclastic vasculitis, TTP/HUS .

Skin: Erythema multiforme, rashes including photosensitivity, alopecia.

Read the entire FDA prescribing information for Valtrex (Valacyclovir Hydrochloride)

How does this medication work? What will it do for me?

Valacyclovir belongs to the class of medications known as antivirals. It is used to treat a viral infection affecting the skin known as shingles (herpes zoster). It is also used to treat cold sores, and to treat and prevent recurrences of genital herpes. It works by interfering with the way the virus reproduces. Valacyclovir works by stopping the virus from multiplying and spreading to nearby healthy cells.

It does not cure shingles, cold sores, or genital herpes, but it does help the sores to heal more quickly, and it relieves pain and discomfort. When used to prevent recurrences of herpes, it also reduces the risk of transmission (spreading) of the infection to others.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

500 mg
Each blue, film-coated, capsule-shaped tablet (caplet) printed with edible white ink with “VALTREX 500 mg” contains valacyclovir HCl equivalent to 500 mg valacyclovir. Nonmedicinal ingredients: carnauba wax, cellulose, crospovidone, hydroxypropyl methylcellulose, Indigotine Aluminum Lake, magnesium stearate, polyethylene glycol, polysorbate 80, povidone, silicon dioxide, and titanium dioxide.

1000 mg
Each white, film-coated, capsule-shaped tablet (caplet) printed with edible blue ink with “GX CF2” contains valacyclovir HCl equivalent to 1000 mg valacyclovir. Nonmedicinal ingredients: carnauba wax, cellulose, crospovidone, hydroxypropyl methylcellulose, magnesium stearate, polyethylene glycol, polysorbate 80, povidone, silicon dioxide, and titanium dioxide.

How should I use this medication?

The recommended adult dose of valacyclovir to treat shingles is 1000 mg 3 times daily for 7 days. The treatment should be started within 72 hours of the onset of the rash.

To treat the first episode of genital herpes, the dose ofvalacyclovir is 1000 mg twice daily for 10 days. Treatment should be started within 72 hours of the onset of symptoms, and ideally within 48 hours for best effectiveness.

To treat recurrent genital herpes, the dose of valacyclovir is 500 mg twice daily for 3 days. The treatment should be started at the first sign or symptom of recurrence.

To prevent recurrences of genital herpes, the recommended dose is 1000 mg once daily. For people with a history of 9 or fewer recurrences per year, the recommended dosage of valacyclovir is 500 mg orally once daily. This dose helps to reduce the risk of transmitting genital herpes to others.

To treat cold sores, the usual dose of valacyclovir is 2000 mg at the first sign of symptoms, followed by another 2000 mg 12 hours later. The treatment should be started at the first sign of a cold sore (tingling, itching, or burning sensations) for best effectiveness.

People with poor kidney function may need lower doses.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way you are using the medication without talking to your doctor.

Valacyclovir can be taken with or without food. If it causes stomach upset, taking it with food may help. Make sure you drink enough water to prevent dehydration while taking valacyclovir.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular dosing schedule. If it is almost time for your next dose, skip the missed dose and continue with your usual dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are allergic to valacyclovir, acyclovir, or any ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain
  • diarrhea
  • dizziness
  • dry mouth
  • flu-like symptoms
  • gas
  • headache
  • heartburn
  • itching
  • joint pain
  • muscle aches
  • nausea
  • skin rash
  • trouble sleeping
  • weakness

Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • behaviour changes
  • confusion
  • depression
  • fast heartbeat
  • hallucinations
  • pain in the side between the ribs and hip or kidney area of the back
  • signs of anemia caused by red blood cell destruction (e.g., abdominal pain, bloody diarrhea, fatigue, nausea, vomiting, confusion, swelling of hands and feet)
  • signs of bleeding (e.g., unusual bruising or bleeding, bleeding gums, unexplained nosebleeds)
  • signs of decreased kidney function (e.g., decreased urine production, loss of appetite, nausea)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, swelling of the face and throat)
  • signs of a severe skin reaction (e.g., a rash combined with fever or discomfort, a rash covering a large area of the body, a rash that spreads quickly, blistering, peeling)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Genital herpes: To reduce the risk of spreading the virus, wash your hands immediately after touching your skin sores. You should avoid intimate contact when live lesions are visible on your skin. The herpes virus can still be spread even when you do not have blisters or sores.

Immunosuppression (weak immune system): People who have a weakened immune system should only use valacyclovir if the benefits outweigh the risks. If you have had an organ transplant, are infected with HIV, or otherwise have a weak immune system, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney disease: Valacyclovir may cause decreased kidney function or kidney failure. People with kidney disease may need a lower dose of this medication. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience signs of decreased kidney function, such as decreased urine production, nausea, fatigue, or muscle twitches or cramps, contact your doctor as soon as possible.

Safer sex: Valacyclovir, when taken in appropriate doses each day, can reduce the risk of passing on genital herpes to sexual partners. It should be used in combination with safer sex practices such as using condoms and dental dams. If you have any questions about practicing safer sex, speak to your doctor.

Systemic infection: The safety and effectiveness of using valacyclovir to treat herpes zoster infection that is inside the body has not been established. This is not an accepted use for this medication.

Pregnancy: Although valacyclovir does not appear to increase the risk of harm to an unborn baby, the safety of valacyclovir use during pregnancy has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking valacyclovir, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: Seniors are more likely to have decreased kidney function than younger adults. A decreased dose of valacyclovir may be required. It is important for seniors to drink enough water while taking this medication, to remain well-hydrated.

What other drugs could interact with this medication?

There may be an interaction between valacyclovir and any of the following:

  • foscarnet
  • mycophenolate
  • tenofovir
  • varicella virus vaccine
  • zidovudine
  • zoster vaccine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

All material copyright MediResource Inc. 1996 – 2020. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source:

Complications With Valtrex

Valtrex is a branded antiviral drug, also known as valcyclovir, that is used for the treatment of infection caused by herpes virus, Epstein Barr (EBV) and Cytomegalovirus (CMV). Valtrex decreases the spread of viruses in the body. There are some notable systemic complications that arise from using Valtrex.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Gastrointestinal Complications

Valtrex may result in gastrointestinal complications. The various gastrointestinal effects that are usually observed include:

  • abdominal discomfort
  • nausea
  • vomiting
  • dehydration,
  • even the inflammation of the liver
  • also known as hepatitis

Liver symptoms are seen because the liver is responsible for the processing of drugs in the body. These symptoms can diminish over time and can be improved by consuming Valtrex with meals.


Headaches can result from the use of Valtrex. These headaches can be mild to severe in nature and tend to decrease as the body adjusts to Valtrex. Merck Online Manuals reports that headaches can affect about 13 to 38 percent of Valtrex users 3. Normal treatment of such headaches involves the use of pain killers such as ibuprofen. However, severe cases of headaches must be reported to the physician.

Allergic Reactions

Patients using Valtrex may experience allergic reactions. Valtrex has the potential to cause allergic reactions in sensitive individuals. Allergic reactions are marked by the presence of hives, outbreaks of rashes, difficulty with breathing, and the swelling of the throat and facial region. Patients are advised to seek emergency medical intervention when such symptoms arise.

Destruction of Red Blood Cells

Destruction of red blood cells can occur in patients taking Valtrex. Red blood cells are mainly responsible for delivering oxygen to the tissues and removing carbon dioxide from the body. The destruction of red blood vessels results in development of anemia. The signs of decreased numbers of red blood cells include:

  • red spots on the skin
  • fever
  • bloody diarrhea
  • bruising
  • yellow pigment in the skin
  • reduced urination
  • weakness
  • fainting


Neutropenia is one of the common complications associated with the use of Valtrex. Neutropenia is a blood disorder characterized by a decreased number of white blood cells in the blood. Neutropenia tends to affect about 18 percent of persons taking Valtrex. This often results in a weakened immune system, making the patients more likely to acquire infection and creating a longer wound healing time.

Do not take this medication if you are allergic to valacyclovir, acyclovir, or any ingredients of the medication.

About valaciclovir

Type of medicine An antiviral medicine
Used for To prevent or treat viral infections in adults and in young people
Also called Valacyclovir (in US); Valtrex®
Available as Tablets

Valaciclovir is known as a pro-drug. Once inside your body it is broken down into an active ingredient called aciclovir. It is used to treat infections caused by two common viruses – herpes zoster and herpes simplex. The herpes zoster virus is the cause of shingles. Herpes simplex viruses cause cold sores, and genital herpes. You will have been prescribed valaciclovir to treat (or prevent further episodes of) one of these infections.

Valaciclovir works by preventing viruses from multiplying, and this reduces the severity of the infection and stops it from spreading.

As well as treating infections, valaciclovir is also prescribed to prevent some viral infections from occurring. This is particularly the case in people who have had an organ transplant and are at risk of infection from a virus called cytomegalovirus.

Before taking valaciclovir

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking valaciclovir it is important that your doctor knows:

  • If you are pregnant or breastfeeding.
  • If you have any problems with the way your kidneys work.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.

How to take valaciclovir

  • Before you start the treatment, read the manufacturer’s printed information leaflet from inside the pack. It will give you more information about valaciclovir, and it will also provide you with a full list of the side-effects which you could experience from taking it.
  • Your dose will depend upon the type of infection you have, so take the tablets exactly as your doctor tells you to. Typically, doses range from 500 mg to 2 g, taken 1-4 times daily. Your doctor or pharmacist will tell you what dose is right for you, and this information will also be printed on the label of the pack to remind you about what the doctor said to you.
  • Space out your doses evenly during the day. Swallow the tablets with a drink of water. You can take valaciclovir tablets either with or without food.
  • Even if you feel your infection has cleared up, keep taking valaciclovir until the course is finished (unless your doctor tells you to stop sooner). A short course of treatment commonly lasts for up to 10 days. You will be prescribed a longer course than this if you are taking it to prevent further episodes of infection, or following an organ transplantation.
  • If you forget to take a dose, take it as soon as you remember and then continue as before. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a missed dose.

Getting the most from your treatment

  • You should drink plenty while you are on valaciclovir to keep your kidneys working well. Drinking water is best, but hot drinks and non-alcoholic cold drinks are also suitable.
  • Valaciclovir could cause your skin to become more sensitive to sunlight than it is usually. Avoid strong sunlight and sunbeds, and use a sun cream with a high sun protection factor until you know how your skin reacts.
  • If you have been prescribed valaciclovir for genital herpes, do not have sex while you have sores or blisters. Even after these have healed, there is still a small chance that you may pass on the virus when you have sex – using a condom reduces this risk.
  • If you are having an operation or any other medical treatment, tell the person carrying out the treatment that you are taking valaciclovir.

Can valaciclovir cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with valaciclovir. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer’s printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer’s information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common valaciclovir side-effects (these affect more than 1 in 10 people) What can I do if I experience this?
Headache Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor
Common valaciclovir side-effects
(these affect less than 1 in 10 people)
What can I do if I experience this?
Feeling sick (nausea) or being sick (vomiting) Stick to simple foods – avoid fatty or spicy meals
Feeling dizzy Do not drive and do not use tools or machines while affected
Diarrhoea Drink plenty of water to replace any lost fluids
Itching or skin rash If troublesome, speak with your doctor

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.

How to store valaciclovir

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Generic name: Valacyclovir (val a SYE kloe veer)

Drug Class: Antiviral

Table of Contents

  • Overview
  • How to Take It
  • Side Effects
  • Warnings & Precautions
  • Drug Interactions
  • Dosage & Missing a Dose
  • Storage
  • Pregnancy or Nursing
  • More Information


Valtrex (Valacyclovir) is an antiviral medication used to treat infections caused by certain viruses. It helps the body fight infection by slowing the growth and spread of the herpes virus. It is used to treat shingles (caused by herpes zoster), genital herpes, and cold sores around the mouth.

Valtrex is also a treatment for cold sores in children over the age of 12 years old and as a chickenpox medication in children who are over the age of 2 years.

This information is for educational purposes only. Not every known side effect, adverse effect, or drug interaction is in this database. If you have questions about your medicines, talk to your health care provider.

How to Take It

Valacyclovir comes as a tablet to take by mouth. It is usually taken every 8 hours (three times a day) for 7 days to treat shingles. To treat genital herpes it is usually taken twice a day for 5 days. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take valacyclovir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. Use this medication as soon as possible after symptoms appear.

Side Effects

Side effects that may occur while taking this medicine include:

  • stomach pain
  • joint pain
  • headache
  • constipation
  • vomiting
  • cold symptoms, e.g., nasal congestion / runny nose / sneezing
  • nausea
  • loss of voice
  • muscle aches
  • dizziness

Contact your doctor immediately if you experience:

  • confusion
  • shortness of breath
  • itching
  • mouth sores
  • skin rash
  • yellowness of the skin or eyes
  • blood in urine
  • hallucinations
  • hyperventilation
  • bleeding or bruising easily
  • irritability
  • chills
  • fast or irregular heartbeat
  • bleeding gums
  • difficulty speaking
  • loss of consciousness
  • fever

Warnings & Precautions

  • Get immediate medical attention if you experience breathing difficulty, itching, rash, or swelling, or severe dizziness.
  • If you are allergic to acyclovir (Zovirax), valacyclovir, or any other drugs, let your doctor know immediately.
  • Inform your doctor of what medications you are currently taking, especially probenecid (Benemid) or cimetidine (Tagamet). This also includes prescription, non-prescription, and vitamins.
  • If you experience side effects such as: unsteady movements, mood or mental changes, difficulty speaking, or any changes in urine output, contact your doctor immediately.
  • Inform your doctor if you have or have ever had kidney or liver disease, problems with your immune system, human immunodeficiency virus infection (HIV), or acquired immunodeficiency syndrome (AIDS).
  • Do not give this medication to a child without first consulting your doctor.
  • For an overdose, seek medical attention immediately. For non emergencies, contact your local or regional poison control center at 1-800-222-1222.

Drug Interactions

Before taking any new medicine, either prescription or over-the-counter, check with your doctor or pharmacist. This includes supplements and herbal products.

Dosage & Missed Dose

Valtrex should be taken exactly as prescribed by your doctor, usually in evenly spaced intervals. It is available in oral tablet form, in 500 mg and 1 gram. For the best results, take it at the very first sign of an outbreak.

As soon as a rash appears for chickenpox or shingles, take this medication immediately. If you feel tingling, itching or burning (e.g., cold sores or genital herpes) take this medication as soon as possible.

Take your next dose as soon as you remember. If it is time for your next dose, skip the missed dose and go back to your regular schedule. Do not double doses or take extra medicine to make up for the missed dose.


Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (preferably not in the bathroom). Throw away any medication that is outdated or no longer needed.


Valtrex should be used only when clearly needed during pregnancy. Talk to your doctor about the risks and benefits.

It can pass into breast milk, but is unlikely to harm a nursing infant. Before breast-feeding, talk with your doctor.

More Information

For more information, talk to your doctor, pharmacist or health care provider, or you can visit this website, for additional information from the manufacturer of this drug.


Herpes Zoster Virus (shingles)

Shingles is an infection caused by a herpes virus called varicella-zoster, which also causes chickenpox. Of those who had chickenpox earlier in life, 3–5 percent of them will develop shingles, usually after the age of 50. Even though the chickenpox healed, the virus lives quietly in nerves near the spinal cord. If the immune system weakens enough, the virus can become active. Instead of coming back as chickenpox (varicella), it comes back as shingles (zoster).

Up to 95 percent of people in the U.S. have antibodies for varicella-zoster.

For people living with HIV, shingles is more than 15 times more likely to occur, at any CD4 count but more often in those with counts below 200. For CD4 counts below 50, there’s a higher risk of zoster infection in other parts of the body such as the retina of the eye, which can result in rapid blindness.

What are the symptoms?

When shingles occurs, it only affects one side of the body, usually in the form of a belt-like streak along a single line of nerves. The most common site is the back, upper abdomen, neck or face. It can also affect the eyes and more rarely the inner ear. Shingles can be very painful, but it can be treated.

The first symptoms are often fever, chills, tiredness, headache, and upset stomach, which can lead people to think they have the flu. These are often followed by sensations of numbness, tingling or pain on one side of the body or face. Many describe the pain as burning, throbbing and stinging, with intermittent sharp stabs of severe pain. Some people experience severe itching or aching rather than pain.

After several days of symptoms, a rash develops that extends from the middle of the body outward. The rash will be made up of clusters of small, clear, fluid-filled blisters on reddened skin. Within several days, the blisters will turn yellow, dry up, and crust over. This may take longer in those with weakened immune systems. It can then take two or more weeks for the crusted shingles to heal completely, sometimes leaving scars.

In 10–25 percent of cases, shingles can occur in the eye. Symptoms range from pain and redness of the eye to impaired vision and chronic twitching of the eyelid. In worst cases, this can lead to permanent damage and blindness. Also, rarely, shingles can spread to the nerves in the inner ear, which can lead to hearing loss, vertigo and loss of balance.

It can take up to six weeks for shingles pain to disappear. Sometimes, shingles can do long-lasting damage to a nerve, which may result in pain, numbness, or tingling for months or years afterwards, called post-herpetic neuralgia. Shingles recurs in about 1 out of 3 people living with HIV. And 10–15 percent report ongoing neuralgia from the previous shingles outbreak.

How is shingles diagnosed?

Initial flu-like symptoms can be mistaken for other diseases. As soon as the rash develops, however, shingles is fairly easy to diagnose, as it is rather unique in its look. Your doctor may diagnose it by simply by looking at it and have you start treatment immediately. To be sure, your doctor can swab the rash and send the sample to a lab to look for the virus.

How is shingles treated?

Like most herpes viruses, varicella-zoster cannot be cured. However, shingles can be treated, which can speed up healing time, reduce pain, and delay or prevent shingles from recurring. Most of the time, pills are taken by mouth. However, if the infection is severe or doesn’t respond to the pills, IV treatment in a hospital may be necessary.

Treatment works best if it is started within the first three days of symptoms. Thus, it’s best to contact your health provider as soon as you notice burning, sharp pain, tingling, or numbness in or under your skin on one side of your body or face. Three treatments are available:

Acyclovir (Zovirax). Acyclovir has been studied in people living with HIV and herpes simplex but not shingles, and rarely causes side effects. The oral dose is taken five times a day, usually for 7–10 days. Acyclovir has been studied during pregnancy and appears safe to use.

Valacyclovir (Valtrex): Valacyclovir has been studied in people living with HIV and herpes simplex but not shingles, and is a preferred choice of treatment. It is taken three times a day for 7–10 days. Valacyclovir rarely causes side effects, appears safe to use during pregnancy, and offers better dosing.

Famciclovir (Famvir): Famciclovir is also a preferred choice and is taken by mouth three times a day for 7–10 days. Famciclovir appears safe to use during pregnancy, and offers better dosing options.

In some cases, shingles does not respond to these drugs, probably due to the forming of drug-resistant virus. Fortunately, this has occurred in only a few people living with HIV. Because these drugs are similar, simply switching them is not usually effective.

Currently, foscarnet (Foscavir) is the most common treatment for acyclovir-resistant shingles. It must be given by IV, usually three times a day, often in a hospital or under close supervision of an in-home nurse.

Painkillers (Tylenol, Advil, etc.) can also be used to manage the discomfort of shingles. Stronger painkillers, including those taken by mouth or applied to the skin (Lidoderm, etc.), are available with a doctor’s prescription. Corticosteroids, like prednisone, may also be prescribed. However, there are no data on the use of immune suppressing drugs like prednisone to treat shingles in people with HIV.

During a case of shingles, keep the sores and area around the sores as clean and dry as possible. This will help it heal well. Keeping them clean can also prevent bacterial infection. Some doctors recommend warm showers to clean the affected area. Afterwards, towel dry gently, or use a hair dryer on a low or cool setting. To prevent chaffing, avoid tight-fitting clothes. Most creams and lotions do no good and may even irritate the area.

Can shingles be prevented?

Yes. Shingles can be prevented through vaccines and good hygiene.

A person cannot transmit shingles to someone who has already had chickenpox or has been vaccinated for it. However, the shingles rash can “shed” the virus and infect a person who has not had chickenpox or has not been vaccinated. Therefore, refrain from touching shingles sores and cover the rash to prevent exposure to others.

If an adolescent or adult living with HIV who has never had chickenpox (or antibodies to varicella-zoster) but has been exposed to shingles, they could take post-exposure prophylaxis. In this case, VariZIG should be used within 10 days but ideally within 96 hours of the exposure to reduce symptoms if transmission occurred. Since VariZIG is an investigational new treatment, the prescribing doctor would need to make an application to the expanded access program.

There are three vaccines available. The first, Varivax, is typically recommended for children and prevents initial infection and chickenpox. Another vaccine, called Zostavax, is used to protect a person from developing shingles who has had chickenpox. A third vaccine, Shingrix, was approved by the FDA in early 2018.

Varivax is a live virus vaccine and is recommended for children living with HIV who’ve never had chickenpox, are at least eight years old, and have a CD4 count of at least 200. While there aren’t any studies of adolescents and adults with HIV who’ve never had chickenpox, many experts recommend it for older people with HIV, provided that their CD4 count is at least 200. If the Varivax vaccine causes disease—which is rare but possible—acyclovir treatment is recommended. Pregnant women should not get the live vaccine.

Zostavax is a live virus vaccine used to prevent shingles in people who have already had chickenpox. It prevents shingles by 51 percent and neuralgia by 67 percent. However, it is not recommended for adults living with HIV, especially in those with lower CD4 counts. It is probably best that the vaccine be avoided by all people with HIV, regardless of their immune system status, until proper clinical studies are done. Pregnant women should not get the live vaccine.

The Shingrix vaccine provides higher levels of protection than Zostavax (more than 90 percent), and the CDC recommends its use over Zostavax. Although Shingrix is a dead virus vaccine, it has not been studied in people living with HIV or in pregnant women.

Keeping the immune system healthy is the best way to prevent shingles. This means keeping your viral load low and your CD4 cells high using HIV treatment and by adopting a healthy lifestyle. Also, taking lower doses of acyclovir, valacyclovir or famciclovir over time can help prevent shingles from recurring. However, this is usually recommended only for those who have a history of frequent recurrences.

Are there any experimental treatments?

If you would like to find out if you are eligible for any clinical trials involving new treatments for shingles, visit, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email [email protected]

Last Reviewed: January 24, 2019

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