Doxazosin is used in men to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia-BPH). It does not shrink the prostate, but it works by relaxing the muscles in the prostate and part of the bladder. This helps to relieve symptoms of BPH such as difficulty in beginning the flow of urine, weak stream, and the need to urinate frequently or urgently (including during the middle of the night).
Doxazosin belongs to a class of drugs known as alpha blockers.
Doxazosin may cause a sudden drop in your blood pressure, which could lead to dizziness or fainting, usually within a few hours after you take it. This risk is higher when you first start taking this drug, after your doctor increases your dose, or if you restart treatment after you stop taking it. During these times, avoid situations where you may be injured if you faint.
Do not crush or chew extended-release tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split the tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.
The dosage is based on your medical condition and response to treatment.
Take this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. If you miss taking doxazosin for a few days, you may need to restart treatment at a lower dose and gradually increase your dose again. Consult your doctor for more details.
If you are switching from another form of doxazosin to this extended-release form, be sure to follow your doctor's instructions closely.
Tell your doctor if your condition does not improve or if it worsens.
To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
An empty tablet shell may appear in your stool. This effect is harmless because your body has already absorbed the medication.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if you have any serious side effects, including: fainting, shortness of breath, weakness, yellowing eyes/skin, dark urine, easy bleeding/bruising, fever, persistent sore throat.
Get medical help right away if you have any very serious side effects, including: chest pain.
Rarely, males may have a painful or prolonged erection lasting 4 or more hours. If this occurs, stop using this drug and get medical help right away, or permanent problems could occur.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Before taking doxazosin, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers such as prazosin or terazosin; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: stomach/intestine problems (such as short bowel syndrome, chronic constipation, narrow gut, slow gut movement), heart disease (such as congestive heart failure, angina, heart attack in last 6 months), liver disease, low blood pressure, certain eye problems (cataracts, glaucoma).
This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages. See also How to Use section.
Before having surgery (including cataract/glaucoma eye surgery), tell your doctor or dentist if you are taking or have ever taken this medication, and about all the other products you use (including prescription drugs, nonprescription drugs, and herbal products).
Older adults may be more sensitive to the side effects of this drug, especially dizziness and low blood pressure when getting up from a sitting or lying position. These side effects can increase the risk of falling.
During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
If you are also taking a drug to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), your blood pressure may get too low which can lead to dizziness or fainting. Your doctor may need to adjust your medications to minimize this risk.
Other medications can affect the removal of doxazosin from your body, which may affect how doxazosin works. Examples include azole antifungals (such as itraconazole, ketoconazole), boceprevir, macrolide antibiotics (such as clarithromycin), HIV protease inhibitors (such as lopinavir, ritonavir), among others.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe dizziness, fainting.
If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip themissed dose and resume your usual dosing schedule. Do not double the dose to catch up. See also How to Use section.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.Information last revised March 2017. Copyright(c) 2017 First Databank, Inc.
With WebMD's Medicine Cabinet, you can check interactions with drugs.Go to medicine cabinet