Brand Name(s):

  • Minizide®(as a combination product containing Polythiazide, Prazosin)¶


Prazosin and polythiazide should not be the first medicine you use for high blood pressure. Your medications must be carefully adjusted to treat high blood pressure. If you have not been on any medication for high blood pressure before prazosin and polythiazide, check with your doctor again before taking it.

WHY is this medicine prescribed?

The combination of prazosin and polythiazide is used to treat high blood pressure. It is a combination of two medicines. Prazosin, an alpha-block antihypertensive, works by relaxing blood vessels so that blood can flow more easily through the body. Polythiazide, a thiazide diuretic ('water pill'), causes the kidneys to get rid of unneeded water and salt from the body into the urine.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

HOW should this medicine be used?

The combination of prazosin and polythiazide comes as a capsule to take by mouth. It is usually taken two to three times a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take prazosin and polythiazide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

The combination of prazosin and polythiazide controls high blood pressure but does not cure it. Continue to take prazosin and polythiazide even if you feel well. Do not stop taking prazosin and polythiazide without talking to your doctor.

What SPECIAL PRECAUTIONS should I follow?

Before taking prazosin and polythiazide,

  • tell your doctor and pharmacist if you are allergic to prazosin, polythiazide, other thiazide drugs, chlorothiazide, sulfa drugs, doxazosin, terazosin, or any other drugs.
  • tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially anti-inflammatory medications such as ibuprofen (Motrin, Nuprin) or Naproxen (Aleve); beta-adrenergic blockers such as atenolol (Tenormin), carteolol (Cartrol), labetalol (Normodyne, Trandate), metoprolol (Lopressor), nadolol (Corgard), propranolol (Inderal), sotalol (Betapace), and timolol (Blocadren); clonidine (Catapres); corticosteroids (such as prednisone [Deltasone, Orasone, others], betamethasone [Celestone], cortisone [Cortone], dexamethasone [Decadron, others], hydrocortisone, or methylprednisolone [Medrol, Solu-Medrol, others]); guanadrel (Hylorel); guanethidine (Ismelin); indomethacin (Indocin); lithium (Eskalith, Lithobid), medications for diabetes; other medications for high blood pressure; probenecid (Benemid); reserpine (Serpalan, Serpasil); verapamil (Calan); and vitamins and herbal products.
  • tell your doctor if you have or have ever had asthma; liver, thyroid, or kidney disease; high cholesterol; diabetes; gout; difficulty urinating; or systemic lupus erythematosus (SLE).
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking prazosin and polythiazide, call your doctor immediately.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking prazosin and polythiazide.
  • you should know that this drug may make you drowsy or dizzy. Do not drive a car or operate machinery for 24 hours after the first time you take prazosin and polythiazide or after your dose is increased.
  • remember that alcohol can add to the drowsiness caused by this drug.
  • plan to avoid unnecessary or prolonged exposure to sunlight and to wear protective clothing, sunglasses, and sunscreen. Prazosin and polythiazide may make your skin sensitive to sunlight.
  • you should know that this drug may make you dizzy when you get up from sitting or laying down. Be sure you get up slowly.

What SPECIAL DIETARY instructions should I follow?

Follow your doctor's directions. They may include following a daily exercise program or a low-salt or low-sodium diet, potassium supplements, and increased amounts of potassium-rich foods (e.g., bananas, prunes, raisins, and orange juice) in your diet.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one. Check with your doctor if you have missed two or more doses.

What SIDE EFFECTS can this medicine cause?

Prazosin and polythiazide may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • dizziness
  • drowsiness
  • weakness
  • tiredness
  • blurred vision
  • ringing in the ears
  • stuffy nose
  • bloody nose
  • headache
  • upset stomach
  • vomiting
  • diarrhea
  • muscle weakness
  • thirst or dry mouth
  • abdominal pain
  • constipation
  • joint pain
  • cramps or muscle pain
  • decreased or increased urination
  • hair loss
  • loss of appetite
  • decreased sexual ability or interest

If you experience any of the following symptoms, call your doctor immediately:

  • difficulty breathing
  • difficulty swallowing
  • fast heartbeat
  • irregular heartbeat
  • chest pain
  • sore throat with fever
  • fainting
  • unusual bleeding or bruising
  • severe skin rash with peeling skin
  • yellowing of the skin or whites of the eyes
  • infection

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at Web Site] or by phone [1-800-332-1088].

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

What should I do in case of OVERDOSE?

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your blood pressure should be checked regularly to determine your response to prazosin and polythiazide.

Before having laboratory tests, tell your doctor and the laboratory personnel that you are taking prazosin and polythiazide. This drug interferes with some laboratory tests.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

¶These branded products are no longer on the market and only generic alternatives are available.

AHFS® Consumer Medication Information. © Copyright, The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Last Reviewed: August 1, 2010.