How to take cephalexin 4 times a day?

Cephalexin, Oral Capsule

This dosage information is for cephalexin oral capsule. All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

Forms and strengths

Generic: Cephalexin

  • Form: Oral capsule
  • Strengths: 250 mg, 500 mg, 750 mg

Brand: Keflex

  • Form: Oral capsule
  • Strengths: 250 mg, 500 mg, 750 mg

Dosage for respiratory tract infection

Adult dosage (ages 18 to 64 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 15 to 17 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 1 to 14 years)

25–50 mg/kg of body weight per day taken in divided doses. Your doctor may double your dose for severe infections.

Child dosage (ages 0 to 1 years)

This medication hasn’t been studied in children younger than 1 year for this condition.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for otitis media (middle ear infection)

Adult dosage (ages 18 to 64 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 15 to 17 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 1 to 14 years)

75–100 mg/kg of body weight per day given in equally divided doses every 6 hours.

Child dosage (ages 0 to 1 years)

This medication hasn’t been studied in children younger than 1 year for this condition.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for skin and skin structure infection

Adult dosage (ages 18 to 64 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 15 to 17 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 1 to 14 years)

25–50 mg/kg of body weight per day taken in divided doses. Your doctor may double your dose for severe infections.

Child dosage (ages 0 to 1 years)

This medication hasn’t been studied in children younger than 1 year for this condition.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for bone infections

Adult dosage (ages 18 to 64 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 15 to 17 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. If you have a severe infection, your doctor may give you a larger dose.

Child dosage (ages 1 to 14 years)

25–50 mg/kg of body weight per day taken in divided doses. Your doctor may double your dose for severe infections.

Child dosage (ages 0 to 1 years)

This medication hasn’t been studied in children younger than 1 year for this condition.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Dosage for genitourinary (urinary tract) infection

Adult dosage (ages 18 to 64 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. Your doctor may give you a larger dose if you have a severe infection.

Child dosage (ages 15 to 17 years)

1–4 grams per day taken in divided doses. The usual dose is 250 mg taken every 6 hours, or a dose of 500 mg every 12 hours may be given. Your doctor may give you a larger dose if you have a severe infection.

Child dosage (ages 1 to 14 years)

25–50 mg/kg of body weight per day taken in divided doses. Your doctor may double your dose for severe infections.

Child dosage (ages 0 to 1 years)

This medication hasn’t been studied in children younger than 1 year for this condition.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. Your doctor may start you on a lowered dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Special dosage considerations

For adults and children (15 years of age and older) with kidney problems:

  • People with a creatinine clearance (CrCL) of 30–59 mL/min: maximum daily dose should not exceed 1 g
  • People with a CrCL of 15 to 29 mL/min: 250 mg taken every 8 or 12 hours
  • People with a CrCL of 5 to 14 mL/min: 250 mg every 24 hours
  • People with a CrCL of 1 to 4 mL/min: 250 mg every 48 or 60 hours

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always speak with your doctor or pharmacist about dosages that are right for you.

Keflex

SIDE EFFECTS

The following serious events are described in greater detail in the Warning and Precautions section:

  • Hypersensitivity reactions
  • Clostridium difficile-associated diarrhea
  • Direct Coombs’ Test Seroconversion
  • Seizure Potential
  • Effect on Prothrombin Activity
  • Development of Drug-Resistant Bacteria

Clinical Trials Experience

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

In clinical trials, the most frequent adverse reaction was diarrhea. Nausea and vomiting, dyspepsia, gastritis, and abdominal pain have also occurred. As with penicillins and other cephalosporins, transient hepatitis and cholestatic jaundice have been reported.

Other reactions have included hypersensitivity reactions, genital and anal pruritus, genital candidiasis, vaginitis and vaginal discharge, dizziness, fatigue, headache, agitation, confusion, hallucinations, arthralgia, arthritis, and joint disorder. Reversible interstitial nephritis has been reported. Eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia, and slight elevations in aspartate transaminase (AST) and alanine transaminase (ALT) have been reported.

In addition to the adverse reactions listed above that have been observed in patients treated with KEFLEX, the following adverse reactions and other altered laboratory tests have been reported for cephalosporin class antibacterial drugs:

Other Adverse Reactions

Fever, colitis, aplastic anemia, hemorrhage, renal dysfunction, and toxic nephropathy.

Altered Laboratory Tests

Prolonged prothrombin time, increased blood urea nitrogen (BUN), increased creatinine, elevated alkaline phosphatase, elevated bilirubin, elevated lactate dehydrogenase (LDH), pancytopenia, leukopenia, and agranulocytosis.

Read the entire FDA prescribing information for Keflex (Cephalexin)

Keflex Side Effects

Generic Name: cephalexin

Medically reviewed by Drugs.com. Last updated on Jan 22, 2019.

  • Overview
  • Side Effects
  • Dosage
  • Professional
  • Tips
  • Interactions
  • More

Note: This document contains side effect information about cephalexin. Some of the dosage forms listed on this page may not apply to the brand name Keflex.

For the Consumer

Applies to cephalexin: oral capsule, oral powder for suspension, oral tablet

Along with its needed effects, cephalexin (the active ingredient contained in Keflex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking cephalexin:

More common

  • Diarrhea

Rare

  • Abdominal or stomach pain
  • blistering, peeling, or loosening of the skin
  • chills
  • clay-colored stools
  • cough
  • dark urine
  • diarrhea
  • dizziness
  • fever
  • general tiredness and weakness
  • headache
  • itching or rash
  • joint or muscle pain
  • light-colored stools
  • loss of appetite
  • nausea and vomiting
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • unpleasant breath odor
  • unusual tiredness or weakness
  • upper right abdominal or stomach pain
  • vomiting of blood
  • yellow eyes or skin

Incidence not known

  • Abdominal or stomach cramps or tenderness
  • back or leg pains
  • black, tarry stools
  • bleeding gums
  • bloating
  • blood in the urine or stools
  • chest pain
  • coughing up blood
  • diarrhea, watery and severe, which may also be bloody
  • difficulty with breathing or swallowing
  • fast heartbeat
  • general body swelling
  • hives
  • increased menstrual flow or vaginal bleeding
  • increased thirst
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loss of appetite
  • nosebleeds
  • pain
  • painful or difficult urination
  • pale skin
  • paralysis
  • pinpoint red spots on the skin
  • prolonged bleeding from cuts
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • red or black, tarry stools
  • red or dark brown urine
  • swollen or painful glands
  • tightness in the chest
  • unusual bleeding or bruising
  • unusual weight loss
  • watery or bloody diarrhea

Some side effects of cephalexin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

  • Acid or sour stomach
  • anxiety
  • belching
  • burning feeling in the chest or stomach
  • difficulty with moving
  • dry mouth
  • heartburn
  • hyperventilation
  • indigestion
  • irregular heartbeats
  • irritability
  • itching of the vagina or genital area
  • muscle pain or stiffness
  • nervousness
  • pain during sexual intercourse
  • pain, swelling, or redness in the joints
  • redness of the skin
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • shaking
  • stomach upset
  • trouble sleeping
  • white or brownish vaginal discharge

For Healthcare Professionals

Applies to cephalexin: oral capsule, oral powder for reconstitution, oral tablet, oral tablet dispersible

General

The most commonly reported side effects included diarrhea, dyspepsia, gastritis, nausea, and vomiting.

Gastrointestinal

Frequency not reported: Diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain, anal pruritus, Clostridium difficile-associated diarrhea/colitis/pseudomembranous colitis

Postmarketing reports: Colitis

Hematologic

Frequency not reported: Direct Coombs’ test seroconversion, decreased prothrombin activity/prolonged prothrombin time, eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia

Postmarketing reports: Aplastic anemia, pancytopenia, leukopenia, agranulocytosis

Dermatologic

Frequency not reported: Urticaria, rash, erythema multiforme, Stevens Johnson syndrome, toxic epidermal necrolysis/exanthematic necrolysis

Hepatic

Frequency not reported: Transient hepatitis, cholestatic jaundice, AST and ALT elevations

Postmarketing reports: Increased bilirubin

Hypersensitivity

Frequency not reported: Hypersensitivity/allergic reactions, angioedema, anaphylaxis

Allergic reactions (including urticaria and angioedema) usually subsided upon treatment discontinuation.

Genitourinary

Frequency not reported: Genital pruritus, genital candidiasis, vulvovaginitis/vaginitis and vaginal discharge

Nervous system

Frequency not reported: Seizure, dizziness, headache

Psychiatric

Frequency not reported: Agitation, confusion, hallucinations

Musculoskeletal

Frequency not reported: Arthralgia, arthritis, joint disorder

Renal

Frequency not reported: Reversible interstitial nephritis

Postmarketing reports: Renal dysfunction, toxic nephropathy, increased blood urea nitrogen, increased creatinine

Other

Frequency not reported: Fatigue

Postmarketing reports: Fever

Immunologic

Frequency not reported: Development of drug-resistant bacteria development

Metabolic

Postmarketing reports: Increased alkaline phosphatase, increased lactate dehydrogenase (LDH)

Cardiovascular

Postmarketing reports: Hemorrhage

1. “Product Information. Keflex (cephalexin).” Dista Products Company, Indianapolis, IN.

2. “Product Information. Daxbia (cephalexin).” Crown Laboratories, Johnson City, TN.

3. Cerner Multum, Inc. “UK Summary of Product Characteristics.” O 0

4. Cerner Multum, Inc. “Australian Product Information.” O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

Related questions

  • Can you take cephalexin for a spider bite?
  • Cephalexin – is this a drug that can be abused by teens?
  • Cephalexin – can this be used to treat an abscess in the mouth or gum infection?
  • If people are allergic to amoxicillin can they take cephalexin?
  • What is the best antibiotic to treat strep throat?
  • Can you take antibiotics while pregnant?

Medical Disclaimer

More about Keflex (cephalexin)

  • During Pregnancy or Breastfeeding
  • Dosage Information
  • Patient Tips
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  • Drug Interactions
  • Compare Alternatives
  • Support Group
  • Pricing & Coupons
  • En Español
  • 69 Reviews
  • Generic Availability
  • Drug class: first generation cephalosporins

Consumer resources

  • Keflex
  • Keflex (Cephalexin Capsules and Tablets)
  • Keflex (Cephalexin Suspension)
  • Keflex (Advanced Reading)

Other brands: Biocef, Daxbia

Professional resources

  • Keflex (AHFS Monograph)
  • … +1 more

Related treatment guides

  • Bladder Infection
  • Bacterial Infection
  • Bacterial Endocarditis Prevention
  • Acne
  • … +7 more

Cephalexin

Cephalexin, an antibiotic in the cephalosporin family, is used to treat infections caused by bacteria.

Cephalexin is prescribed to treat respiratory tract, middle ear, skin, bone, and urinary tract infections (UTI).

It’s also used to prevent infections caused by streptococcal bacteria, including prevention of rheumatic fever. Cephalexin isn’t recommended for sinus infections.

Cephalexin is sometimes called a first-generation cephalosporin because it was one of the first cephalosporins developed and marketed.

It was approved by the Food and Drug Administration in 1971 and was first sold by Eli Lilly and Company under the brand name Keflex; today Keflex is made and sold by Shionogi Inc.

It’s also available as a generic medication in tablet or liquid form (called suspension).

Cephalexin and other cephalosporin antibiotics are broad-spectrum antibiotics, meaning they’re used to treat a wide range of infections caused by many different bacteria.

Cephalexin kills susceptible bacteria by interfering with the bacteria’s ability to make cell walls, which are necessary for the bacteria cells to survive.

Cephalexin should only be used when there’s strong evidence to support its use. Overusing broad-spectrum antibiotics can lead to serious infections from drug-resistant bacteria (“superbugs”).

Treating colds or flu symptoms with broad-spectrum antibiotics can lead to antibiotic resistance and more severe infections that are harder to treat.

Cephalexin Warnings

If you’re allergic to penicillin, there’s about a 10 percent chance that you will also be allergic to cephalexin.

You could be at higher risk for side effects from cephalexin if you have a history of liver, kidney, or colon disease, so tell your doctor about any of these conditions as well.

Like other antibiotics, cephalexin may cause an overgrowth of bacteria called Clostridium difficile in your colon. Toxins produced by C. difficile can cause diarrhea and a condition called pseudomembranous colitis.

Being on other antibiotics may also increase your risk for pseudomembranous colitis, so tell your doctor about any recent antibiotic use.

Cephalexin and Pregnancy

Cephalexin should be used only if clearly needed during pregnancy, and with caution during breastfeeding.

Tell your doctor if you are or may become pregnant or if you are breastfeeding.

Cephalexin for Dogs

Veterinarians often prescribe cephalexin to dogs with bacterial infections including skin, bone, urinary tract, respiratory, and other infections.

The drug can be given with food and is usually well-tolerated by dogs, but some may have side effects including nausea or vomiting.

Cephalexin should be avoided in animals that have had an allergic reaction to penicillins or other cephalosporin antibiotics.

Let me start out by saying that I am sharing personal health information and I have waived my right to privacy on this specific matter.
I recently went to see my primary care provider. He is an excellent physician whom I trust. He prescribed an antibiotic for a local infection. We spoke about the options for antibiotics and decided on a medication that would most likely cover the microbial that had caused the infection while taking into consideration side effects and cost. Away I went with my prescription to the local retail pharmacy. That is when the problem began. I was to take the medication 4 times a day approximately 6 hours apart. If that was not enough, I had to make sure that I was taking the medication on an empty stomach, 1 hour prior to eating and 2 hours after my last meal. As many of you may know, I have spent a great deal of my career over the last 10 years on the issue of medication adherence. I am aware of the challenges that dosing and timing can bring to an individual and how they can affect adherence. That being said, I never really understood how significant that challenge can be. I tried—believe me—to fi nd a way to adhere to this medication. First, I wanted to rid myself of the infection and the evil germs that had caused the infection. Secondly, I felt that I needed to “walk the talk” regarding medication adherence. It did not seem appropriate for an adherence spokesperson to be nonadherent. This was no easy task. I found myself having to call my local pharmacist not once but twice over a 48-hour period to fi nd out how strict I had to be on the “every 6 hours” timing. I then had to call again to fi nd out if could I shorten the “empty stomach” rule some and by the way, does empty stomach include liquids?
So what were the lessons learned here and why does it matter? First off, if we want people to be adherent to their medications we need to take timing and directions into consideration. This means that the healthcare consumer, the doctor, and the payer have to be thoughtful of the matter. Physicians need to be aware that taking a medication 4 times a day is very difficult. Six AM, noon, 6 PM, and midnight is not a schedule that most people, including myself, can keep for any length of time. In addition this creates a very small window of opportunity to eat and still follow the directions on the medication. I would argue that these issues are as important as medication effectiveness, side effects, and cost. Secondly, patients need to be realistic about their capability to follow their provider’s directions and speak up prior to agreeing to take the medication. Lastly, it is important that the Pharmacy and Therapeutics (P&T) committees be thoughtful of the scheduling realities of QID medications. Most P&T committees look at dosing as one of the attributes of a drug when evaluating coverage. Unfortunately, it often looked at on the basis of patient convenience only. I think we need to broaden our thought processes.
I do understand that there are some conditions that absolutely require medications that are taken more often than most of us would like; historically, human immunodeficiency virus medications come to mind. That being said, I do believe from personal experience that even the most adherence-conscious people will find medications that need to be taken 4 or, in some cases, even 3 times a day a significant challenge. As we continue to chase the holy grail of medication adherence, we need to be mindful of reality and work together to create our best chance of success.

PMC

Data and Patients

I have successfully treated over 20 patients that presented with brown recluse spider bites with this regimen when it was instituted in the time frame described without significant tissue loss. Minor bites were not included. I will present two patients in this article.

Patient 1 was a 38-year-old white male seen two days post-brown recluse spider bite on the left posterior thigh. He presented with a temperature 101, stated he felt “bad” with malaise. The site had the following characteristics: a 20 cm area of erythema and swelling, 10 cm induration, 4 cm bullous grey-white-blue center, 1 cm stab wound, (I and D attempt by walk-in clinic). The regimen for this patient consisted of the following: tetanus up to date, cephalexin 500 bid, prednisone 100mg/day, one coated aspirin daily, Domeboro® compresses, Spandex/Telfa/Bactroban®, Prilosec OTC®. Followed up two days later (four days post-bite), and the patient was afebrile and felt fine, erythema and swelling were decreased, induration was 7 cm × 5 cm, bullous area unchanged, prednisone level was decreased to 80 mg/day with directions to go to 60mg/day in three days. Followed up nine days post bite, and the erythema and swelling were gone, 4 cm induration remained, central area was 2 cm, ½ cm of white/blue avascularity was noted, prednisone taper schedule initiated (serum AM Cortisol levels checked). Followed up 16 days post bite and found there was a 3 cm induration and a 1 cm ulcer (at stab wound site). The final result was complete healing with no tissue loss and minimal scarring

Patient 2 presented with a brown recluse bite on left anterior thigh three days post bite. (See photos, above.) Patient saw urgent care facility prior to seeing my office, and they treated the site with I and D with drain placement. The site had the following characteristics: 20 cm × 20 cm margin of erythema and swelling, 5 cm of induration, 3 cm of white-grey-bluish center with stab wound and drain, and lymphangitic proximal toxic streaking. The patient was afebrile but “achy”. The regimen for this patient consisted of the following: tetanus up to date, prednisone 100 mg/day × 2, then 80 mg/day, one coated aspirin daily, Prilosec OTC®, cephalexin 500 bid, drain removal, Dome Boro/Bactroban. Followed up 10 days post-bite and found the erythema decreased in intensity to faint pink and swelling had decreased. There was a 5 cm × 4 cm whitish area centrally with 2 cm × 2 cm × 1 cm purpuric area containing the iatrogenic “wound”. At this point, the prednisone was decreased to 60 mg/day. Followed up 21 days post-bite and found the erythema and swelling are gone, induration 3 cm × 2 cm, hypovascular area smaller, prednisone tapering initiated. Followed up five weeks post bite and found 2 cm × 1½ induration. On the 34th day post bite, a 4 mm ulcer remained. On the 55th day post bite, area was completely healed and only a tiny scar remains.

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