Doxazosin mesylate 4 mg


Doxazosin is the generic name of the prescription drug Cardura, which is used to treat high blood pressure (hypertension) and symptoms of benign prostatic hyperplasia, or BPH (an enlarged prostate).

Doxazosin belongs to a class of medications known as alpha-blockers.

It lowers blood pressure by relaxing the blood vessels, so blood can flow more easily, and it helps relieve symptoms of an enlarged prostate by relaxing the muscles of the bladder and prostate, which improves urinary flow.

Doctors may also prescribe doxazosin to treat kidney stones, bladder problems in women, or other conditions.

Doxazosin was approved by the Food and Drug Administration in 2005, and is made and sold by Pfizer, Inc., under the brand name Cardura.

Several manufacturers also make generic versions of the medication. .

Doxazosin comes as a tablet or extended-release tablet to take by mouth. Your doctor will probably start this medication at a low dose and gradually increase it.

In 2000, a part of the study known as the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) came to a halt because researchers found doxazosin was less effective than a simple diuretic, and patients on doxazosin had a 25 percent higher rate of cardiovascular disease and twice the rate of congestive heart failure.

However, Pfizer’s sales of the drug were largely unaffected by the study.

Doxazosin Warnings

This medication controls symptoms but does not cure any disease. You should continue to take doxazosin even if you feel well.

Your blood pressure or prostate will need to be checked often while you are on doxazosin, so you should visit your doctor regularly.

Doxazosin lowers blood pressure and may cause fainting or dizziness, especially when you first start taking it or when you first wake up. You should alert your doctor if you experience severe dizziness or fainting.

The medication may also impair thinking or reactions. Be careful when driving or performing other activities that require alertness.

Doxazosin may affect your pupils during cataract surgery. Tell your doctor if you are on this medication prior to having this type of procedure.

Doxazosin and Pregnancy

It’s not known whether doxazosin will harm an unborn baby. You should tell your doctor if you are pregnant or might become pregnant while taking this medication.

It’s also not known whether the drug passes into breast milk or if it could harm a breastfeeding baby.

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with doxazosin. Just because a side effect is stated here doesn’t mean that all people taking this medicine will experience that or any side effect.

Often side effects improve as your body gets used to the medicine, but if they are troublesome or don’t go away you should talk to your pharmacist or doctor.

Common doxazosin side effects (affect between 1 in 10 and 1 in 100 people)

  • Dizziness or spinning sensation. If you feel dizzy you should lie down until this passes.
  • A drop in blood pressure when getting up from lying down or sitting that makes you feel dizzy or lightheaded (postural hypotension). If this is a problem try getting up more slowly.
  • Headache.
  • Feeling sleepy.
  • Awareness of your heartbeat (palpitations) or fast heartbeat (tachycardia).
  • Disturbances of the gut such as feeling sick, abdominal pain, dry mouth or indigestion.
  • Inflammation of the lining of the nose (rhinitis) causing a blocked or runny nose.
  • Cough or shortness of breath.
  • Itching.
  • Swollen ankles or feet (peripheral oedema).
  • Pain in the muscles or back.
  • Flu-like symptoms.
  • Urinary tract infections or urinary incontinence.

Uncommon doxazosin side effects (affect between 1 in 100 and 1 in 1000 people)

  • Difficulty sleeping (insomnia).
  • Depression or anxiety.
  • Changes in appetite or weight.
  • Diarrhoea, constipation, vomiting or wind.
  • Skin rash.
  • Increased need to pass urine.
  • Nosebleeds.
  • Numbness.
  • Tremor.
  • Fainting.
  • Sensation of ringing or other noise in the ears (tinnitus).
  • Chest pain or heart attack.
  • Pain in the joints.
  • Gout.
  • Impotence (erectile dysfunction).

Very rare doxazosin side effects (affect fewer than 1 in 10,000 people)

  • Blurred vision.
  • Pins and needles sensations.
  • Hot flushes.
  • Feeling weak or tired.
  • Slow or irregular heartbeat.
  • Inflammation of the liver or jaundice.
  • Enlargement of breasts in men (gynaecomastia).
  • Persistent painful erection of the penis (priapism). Get medical assistance straight away if you experience this.
  • Disturbance in the levels of blood cells in the blood.

Read the leaflet that comes with the medicine or talk to your doctor, nurse or pharmacist if you want any more information about the possible side effects of doxazosin. If you think you have experienced a side effect, did you know you can report this using the yellow card website?

  • What is doxazosin used for and how does it work?
  • What should I know before taking doxazosin?
  • How do I take doxazosin?
  • Can I take other medicines with doxazosin?

Last updated: 16.03.2017

Helen Marshall, BPharm, MRPharmS Helen Marshall, BPharm, MRPharmS A UK registered pharmacist with a background in hospital pharmacy.


Brand Names: Cardura, Cardura XL

Generic Name: doxazosin

  • What is doxazosin (Cardura, Cardura XL)?
  • What are the possible side effects of doxazosin (Cardura, Cardura XL)?
  • What is the most important information I should know about doxazosin (Cardura, Cardura XL)?
  • What should I discuss with my doctor before taking doxazosin (Cardura, Cardura XL)?
  • How should I take doxazosin (Cardura, Cardura XL)?
  • What happens if I miss a dose (Cardura, Cardura XL)?
  • What happens if I overdose (Cardura, Cardura XL)?
  • What should I avoid while taking doxazosin (Cardura, Cardura XL)?
  • What other drugs will affect doxazosin (Cardura, Cardura XL)?
  • Where can I get more information (Cardura, Cardura XL)?

What is doxazosin (Cardura, Cardura XL)?

Doxazosin is an alpha-adrenergic (AL-fa ad-ren-ER-jik) blockers. Doxazosin relaxes your veins and arteries so that blood can more easily pass through them. It also relaxes the muscles in the prostate and bladder neck, making it easier to urinate.

Doxazosin is used to treat hypertension (high blood pressure), or to improve urination in men with benign prostatic hyperplasia (enlarged prostate).

The extended-release form of doxazosin (Cardura XL) is for use only in treating benign prostatic hyperplasia and should not be used to treat hypertension.

Doxazosin may also be used for purposes not listed in this medication guide.

What are the possible side effects of doxazosin (Cardura, Cardura XL)?

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;
  • severe ongoing stomach pain or bloating;
  • new or worsening chest pain;
  • trouble breathing; or
  • a penis erection that is painful or lasts 4 hours or longer.

Common side effects may include:

  • low blood pressure, dizziness;
  • drowsiness;
  • headache; or
  • feeling weak or tired.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about doxazosin (Cardura, Cardura XL)?

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

  • tell your doctor if you have angina (chest pain); low blood pressure; if you have ever had low blood pressure after taking a medication; or if you have or have ever had prostate cancer, or liver disease. If you are taking the extended-release tablet, tell you doctor if you have constipation, short bowel syndrome (a condition where more than half of the small intestine has been removed by surgery or damaged by disease), or narrowing or a blockage of the intestines.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking doxazosin, call your doctor.
  • talk to your doctor about the risks and benefits of taking doxazosin if you are 65 years of age or older. Older adults should not usually take doxazosin to treat high blood pressure, because it is not as safe as other medications that can be used to treat the same condition.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking doxazosin. If you need to have eye surgery at any time during or after your treatment, be sure to tell your doctor that you are taking or have taken doxazosin.
  • you should know that doxazosin may make you drowsy or dizzy. Do not drive a car, operate machinery, or perform dangerous tasks for 24 hours after the first time you take doxazosin or after your dose is increased.
  • you should know that doxazosin may cause dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. This is more common when you first start taking doxazosin, when your dose is increased, or if your treatment has been stopped for more than a few days. To avoid this problem, get out of bed slowly, resting your feet on the floor for a few minutes before standing up. If you experience these symptoms, sit or lie down. If these symptoms do not improve, call your doctor.
  • This list is not complete. Other drugs may interact with doxazosin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

    Further information

    Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use doxazosin only for the indication prescribed.

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

    Copyright 1996-2020 Cerner Multum, Inc. Version: 9.01.

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    More about doxazosin

    • Side Effects
    • During Pregnancy or Breastfeeding
    • Dosage Information
    • Patient Tips
    • Drug Images
    • Drug Interactions
    • Support Group
    • Pricing & Coupons
    • En Español
    • 38 Reviews
    • Drug class: antiadrenergic agents, peripherally acting

    Consumer resources

    • Doxazosin Extended-Release Tablets
    • Doxazosin Tablets
    • Doxazosin (Advanced Reading)

    Other brands: Cardura, Cardura XL

    Professional resources

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