SIDE EFFECTS: Dizziness, headache, drowsiness, stomach upset/pain, or decreased sexual ability/interest may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.

An empty tablet shell may appear in your stool. This is harmless since 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 immediately if any of these unlikely but serious side effects occur: fainting, shortness of breath, weakness.

Tell your doctor immediately if any of these rare but very serious side effects occur: yellowing eyes/skin, dark urine, easy bleeding/bruising, fever, persistent sore throat.

Seek immediate medical attention if any of these rare but very serious side effects occur: vision changes, chest pain, jaw/left arm pain, weakness on one side of the body, slurred speech, confusion.

In the unlikely event you have a painful or prolonged erection lasting 4 or more hours, stop using this drug and seek immediate medical attention, or permanent problems could occur.

A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: 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.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the Cardura XL (doxazosin mesylate extended release tablets) Side Effects Center for a complete guide to possible side effects »

PRECAUTIONS: Before taking doxazosin, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers such as prazosin and 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: prostate cancer, stomach/intestine problems (e.g., short bowel syndrome, chronic constipation, narrowing gut, slow gut movement), heart disease (e.g., congestive heart failure, angina, heart attack in last 6 months), liver disease.

To minimize dizziness and lightheadedness, get up slowly when rising from a sitting or lying position, especially when you first start taking this drug or if your doctor changes your dose. Also, when you first start taking this drug, avoid situations where you may be injured if you faint.

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.

The elderly may be at a greater risk for dizziness and low blood pressure while using this drug.

Before having surgery (including cataract eye surgery), tell your doctor or dentist that you are taking this medication.

During pregnancy, doxazosin should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.