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Polythiazide/ prazosin

Generic name: polythiazide/prazosin [ POL-ee-THYE-a-zide/PRAZ-oh-sin ]
Brand name: Minizide

Polythiazide/ prazosin is used for:

Treating high blood pressure. It may also be used for other conditions as determined by your doctor.

Polythiazide/prazosin is an alpha-blocker and thiazide diuretic combination. It works by widening blood vessels and helping the kidneys eliminate extra fluid from your body, which helps lower blood pressure.

Do NOT use polythiazide/ prazosin if:

  • you are allergic to any ingredient in polythiazide/prazosin or to any other sulfonamide medicine (eg, sulfamethoxazole, glyburide, acetazolamide)
  • you are unable to urinate
  • you are taking dofetilide, ketanserin, or modafinil

Contact your doctor or health care provider right away if any of these apply to you.

Before using polythiazide/ prazosin:

Some medical conditions may interact with polythiazide/prazosin. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have gout, kidney or liver problems, lupus, diabetes, asthma, parathyroid problems, high blood cholesterol or lipid levels, chest pain, heart problems, narcolepsy, or low blood pressure
  • if you have low blood sodium, chloride, potassium, or magnesium levels; or high blood calcium levels
  • if you have recently had nerve surgery

Some MEDICINES MAY INTERACT with polythiazide/prazosin. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Nonsteroidal anti-inflammatory medicines (NSAIDs) (eg, indomethacin) because they may decrease polythiazide/prazosin's effectiveness
  • Barbiturates (eg, phenobarbital), corticosteroids (eg, prednisone), corticotropin (ACTH), medicines for high blood pressure, narcotic pain medicines (eg, codeine, morphine, fentanyl), or verapamil because they may increase the risk of polythiazide/prazosin's side effects
  • Diazoxide or nondepolarizing muscle relaxants (eg, tubocurarine) because the risk of their side effects may be increased by polythiazide/prazosin
  • Lithium because risk of toxicity may be increased by polythiazide/prazosin
  • Beta-blockers (eg, propranolol), bupivacaine, digoxin, dofetilide, ketanserin, nifedipine, or phosphodiesterase type 5 inhibitors (eg, sildenafil, tadalafil, vardenafil) because the risk of their side effects may be increased by polythiazide/prazosin
  • Diabetes medicines (eg, glipizide, metformin), insulin, or modafinil because their effectiveness may be decreased by polythiazide/prazosin

This may not be a complete list of all interactions that may occur. Ask your health care provider if polythiazide/prazosin may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use polythiazide/ prazosin:

Use polythiazide/prazosin as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Take polythiazide/prazosin by mouth with or without food.
  • Polythiazide/prazosin may increase the amount of urine or cause you to urinate more often when you first start taking it. To keep this from disturbing your sleep, try to take your dose before 6 pm.
  • Continue to use polythiazide/prazosin even if you feel well. Do not miss any doses.
  • Taking polythiazide/prazosin at the same time each day will help you remember to take it.
  • Take polythiazide/prazosin regularly to receive the most benefit from it.
  • If you miss a dose of polythiazide/prazosin, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use polythiazide/prazosin.

Important safety information:

  • Polythiazide/prazosin may cause dizziness, drowsiness, lightheadedness, fainting, or blurred vision. These effects may be worse if you take it with alcohol or certain medicines. Use polythiazide/prazosin with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
  • Polythiazide/prazosin may cause dizziness, lightheadedness, or fainting; alcohol, hot weather, exercise, or fever may increase these effects. To prevent them, sit up or stand slowly, especially in the morning. Sit or lie down at the first sign of any of these effects.
  • Tell your doctor or dentist that you take polythiazide/prazosin before you receive any medical or dental care, emergency care, or surgery.
  • Diabetes patients -- Polythiazide/prazosin may raise your blood sugar. High blood sugar may make you feel confused, drowsy, or thirsty. It can also make you flush, breathe faster, or have a fruit-like breath odor. If these symptoms occur, tell your doctor right away.
  • Your doctor may have also prescribed a potassium supplement for you. If so, follow the dosing carefully. Do not start taking additional potassium on your own or change your diet to include more potassium without first checking with your doctor.
  • Polythiazide/prazosin may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to polythiazide/prazosin. Use a sunscreen or wear protective clothing if you must be outside for more than a short time.
  • Patients who take medicine for high blood pressure often feel tired or run down for a few weeks after starting treatment. Be sure to take your medicine even if you may not feel "normal." Tell your doctor if you develop any new symptoms.
  • Lab tests, including kidney function, blood pressure, and blood electrolyte levels, may be performed while you use polythiazide/prazosin. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
  • Use polythiazide/prazosin with caution in the ELDERLY; they may be more sensitive to its effects.
  • Polythiazide/prazosin should not be used in CHILDREN; safety and effectiveness in children have not been confirmed.
  • PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using polythiazide/prazosin while you are pregnant. Polythiazide/prazosin is found in breast milk. Do not breast-feed while taking polythiazide/prazosin.

Possible side effects of polythiazide/ prazosin:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Constipation; dizziness; drowsiness; dry mouth; flushing; headache; lightheadedness, especially when sitting up or standing; numbness or tingling of skin.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; changes in sexual function; confusion; decrease in amount of urine; fainting; gout; muscle pain or cramps; rapid or irregular heartbeat; red, swollen, blistered, or peeling skin; restlessness; seizures; shortness of breath; stomach pain; unusual thirst; unusual tiredness or weakness; unusually dry mouth; vomiting.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include dry mouth; excessive urination followed by a decrease in amount of urine; muscle cramps; severe lightheadedness, especially upon standing; weak or irregular heartbeat.

Proper storage of polythiazide/prazosin:

Store polythiazide/prazosin at room temperature, between 68 and 77 degrees F (20 and 25 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep polythiazide/prazosin out of the reach of children and away from pets.

General information:

  • If you have any questions about polythiazide/prazosin, please talk with your doctor, pharmacist, or other health care provider.
  • Polythiazide/prazosin is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.

This information is a summary only. It does not contain all information about polythiazide/prazosin. If you have questions about the medicine you are taking or would like more information, check with your doctor, pharmacist, or other health care provider.

Issue Date: June 3, 2015

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.