Prazosin/polythiazide (By mouth)


Polythiazide (pol-ee-THYE-a-zide), Prazosin (PRAZ-oh-sin)

Treats high blood pressure.

Brand Name(s)

There may be other brand names for this medicine.

When This Medicine Should Not Be Used

You should not use this medicine if you have had an allergic reaction to prazosin, polythiazide, or sulfa drugs. You should not use this medicine if you have problems with urination.

How to Use This Medicine


  • Your doctor will tell you how much of this medicine to use and how often. Your dose may need to be changed several times in order to find out what works best for you. Do not use more medicine or use it more often than your doctor tells you to.

If a dose is missed:

  • If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are using digoxin (Lanoxin®, Lanoxicaps®) or insulin. Tell your doctor if you also using any blood pressure medicine such as hydrochlorothiazide (HCTZ), atenolol, metoprolol, propranolol, Inderal®, Tenormin®, or Toprol-XL®.
  • Tell your doctor if you are using any medicines that make you sleepy. These include sleeping pills, cold and allergy medicine, narcotic pain relievers, and sedatives.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breast feeding.
  • Make sure your doctor knows if you have diabetes, kidney disease, liver disease, heart disease, gout, lupus, an enlarged prostate, asthma, or any allergies.
  • Make sure your doctor knows if you had surgery recently.
  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
  • Your doctor will need to check your blood or urine at regular visits while you are using this medicine. Be sure to keep all appointments.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Dark-colored urine, pale stools, yellowing of your skin or the whites of your eyes.
  • Dizziness, confusion, or loss of consciousness.
  • Fast or pounding heartbeat, lightheadedness or fainting.
  • Increase in how much or how often you urinate.
  • Muscle twitching or cramps.
  • Numbness, tingling, weakness, or burning pain in your hands, arms, or feet.
  • Painful, prolonged erection of your penis.
  • Shortness of breath, swelling in your hands, ankles, or feet.
  • Sudden and severe stomach pain, nausea, vomiting, or fever.
  • Unusual bleeding, bruising, or weakness.

If you notice these less serious side effects, talk with your doctor:

  • Blurred vision, red eyes, feeling more sensitive to light or colors.
  • Dry mouth, increased thirst, stuffy nose, nosebleed, or ringing in your ears.
  • Feeling nervous, restless, or muscle twitching.
  • Mild fever or headache.
  • Mild nausea, vomiting, diarrhea, constipation, or stomach upset.
  • Mild skin rash, itching or hair loss.
  • Tired feeling or trouble sleeping.
  • Trouble having sex (in men).

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

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