What is doxazosin?
Doxazosin is in a group of drugs called alpha-adrenergic blockers. Doxazosin causes the blood
vessels (veins and arteries) to relax and expand, improving blood flow. Doxazosin also relaxes muscles
in the prostate and bladder neck, making it easier to urinate.
Doxazosin is used to treat hypertension (high blood pressure) and benign prostatic hyperplasia
(enlarged prostate).
Doxazosin may also be used for other purposes not listed in this medication guide.
What should I discuss with my healthcare provider before taking doxazosin?
You should not use this medication if you are allergic to doxazosin or similar medicines such
as prazosin (Minipress), tamsulosin (Flomax), or terazosin (Hytrin).
If you have liver disease or a history of prostate cancer, you may need a dose adjustment
or special tests to safely take doxazosin.
Doxazosin can affect the pupils of your eyes during cataract surgery. If you have cataract
surgery during your treatment with doxazosin, tell the surgeon ahead of time that you take doxazosin.
Do not stop using the medication before surgery unless your surgeon tells you to.
FDA pregnancy category C. It is not known whether this medication is harmful to an
unborn baby. Before taking doxazosin, tell your doctor if you are pregnant or plan to become pregnant
during treatment.
It is not known whether doxazosin passes into breast milk or if it could harm a nursing
baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.
How should I take doxazosin?
Take this medication exactly as it was prescribed for you. Do not take the medication in larger
amounts, or take it for longer than recommended by your doctor. Follow the instructions on your
prescription label. Your doctor may occasionally change your dose to make sure you get the best
results from this medication.
Take each dose with a full glass of water.
Doxazosin lowers blood pressure and may cause dizziness or fainting, especially when you
first start taking it, or when you start taking it again. To avoid falling, take the first dose of doxazosin at
bedtime. You may wish to continue taking this medication only at bedtime if it causes you to feel
light-headed.
You may feel very dizzy when you first wake up. Be careful when standing or sitting up from a
lying position.
If you stopped taking doxazosin for any reason and have started taking it again, you may feel
especially dizzy or light-headed after your first few doses.
To be sure this medication is helping your condition, your blood pressure or prostate will need
to be checked on a regular basis. It is important that you not miss any scheduled visits to your doctor.
If you are being treated for high blood pressure, keep using this medication even if you feel fine.
High blood pressure often has no symptoms.
Store doxazosin at room temperature away from moisture and heat.
What happens if I miss a dose of doxazosin?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the
missed dose and take the medicine at the next regularly scheduled time.
Do not
take
extra medicine to make up the missed dose.
If you miss doses for several days in a row, call your doctor before taking any additional doses.
You may need to use a lower dose of doxazosin for a short time.
Where can I get more information about doxazosin?
Your pharmacist has information about doxazosin written for health professionals that you may read.
What are the possible side effects of doxazosin?
Get emergency medical help if you have any of these
signs of an allergic
reaction:
hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
-
fast or pounding heartbeats;
-
feeling light-headed, fainting;
-
swelling in your hands, ankles, or feet; or
-
penis erection that is painful or lasts 4 hours or longer.
Less serious side effects may include:
-
weakness;
-
headache;
-
dizziness; or
-
diarrhea, stomach pain.
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?
You should not use this medication if you are allergic to doxazosin or similar medicines such
as prazosin (Minipress), tamsulosin (Flomax), or terazosin (Hytrin).
Doxazosin lowers blood pressure and may cause dizziness or fainting, especially when you
first start taking it, or when you start taking it again. To avoid falling, take the first dose of doxazosin at
bedtime. You may wish to continue taking this medication only at bedtime if it causes you to feel
light-headed.
You may feel very dizzy when you first wake up. Be careful when standing or sitting up from a
lying position.
If you stopped taking doxazosin for any reason and have started taking it again, you may feel
especially dizzy or light-headed after your first few doses.
Doxazosin can affect the pupils of your eyes during cataract surgery. If you have cataract
surgery during your treatment with doxazosin, tell the surgeon ahead of time that you take doxazosin.
Do not stop using the medication before surgery unless your surgeon tells you to.
What should I avoid while taking doxazosin?
Doxazosin can cause side effects that may impair your thinking or reactions. Be careful if
you drive or do anything that requires you to be awake and alert.
Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly
and steady yourself to prevent a fall.
Avoid drinking alcohol, which can increase some of the side effects of doxazosin.
What other drugs will affect doxazosin?
Before using doxazosin, tell your doctor if you regularly use other medicines that make you
sleepy (such as cold or allergy medicine, sedatives, narcotic pain medicine, sleeping pills, muscle
relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by
doxazosin.
Tell your doctor about all other medications you use, especially:
This list is not complete and there may be other drugs that can interact with
doxazosin. Tell your doctor about all your prescription and over-the-counter medications, vitamins,
minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication
without telling your doctor.
What happens if I have an overdose of doxazosin?