Brand & Generic Names
Basic Information
- Habit forming? No
- Prescription needed? Yes
- Available as generic? No
- Drug class: Antihypertensive, diuretic (thiazide)
Uses
- Controls, but doesn't cure, high blood pressure.
- Reduces fluid retention (edema) caused by conditions such as
heart disorders and liver disease.
- Treatment for Raynaud's disease.
Dosage & Usage Information
How to take:
Tablet or capsule--Swallow with 8 oz. of liquid. If you can't
swallow whole, crumble tablet or open capsule and take with
liquid or food. Don't exceed dose.
When to take:
At the same times each day.
If you forget a dose:
Take as soon as you remember up to 2 hours
late. If more than 2 hours, wait for next scheduled dose (don't
double this dose).
What drug does:
Expands and relaxes blood vessel walls to lower blood
pressure.
Forces sodium and water excretion, reducing body fluid.
Relaxes muscle cells of small arteries.
Reduced body fluid and relaxed arteries lower blood pressure.
Time lapse before drug works:
4 to 6 hours. May require several
weeks to lower blood pressure.
Don't take with:
Non-prescription drugs without consulting doctor.
See Interaction Section and consult doctor.
Overdose
SYMPTOMS:
Extreme weakness; loss of consciousness; cold, sweaty
skin; weak, rapid pulse; cramps; weakness; drowsiness; coma.
WHAT TO DO:
- Dial 911 (emergency) or O (operator) for an ambulance or
medical help. Then give first aid immediately.
- If patient is unconscious and not breathing, give mouth-to-
mouth breathing. If there is no heartbeat, use cardiac massage
and mouth-to-mouth breathing (CPR). Don't try to make patient
vomit. If you can't get help quickly, take patient to nearest
emergency facility.
- See EMERGENCY Information.
Possible Adverse Reactions or Side Effects
Life-threatening:
Irregular heartbeat, Discontinue. Seek
weak pulse, fast emergency treatment.
heartbeat, difficult
breathing, chest pain.
Common:
Nightmares, vivid
dreams, drowsiness,
dizziness, dry mouth,
stuffy nose.
Infrequent:
- Blurred vision,
abdominal pain,
nausea, vomiting,
difficult breathing.
- Mood change,
headache, dry mouth,
muscle pain, urgent
urination, weakness,
tiredness, weight gain
or loss, runny nose,
joint or muscle pain,
agitation, depression,
rash, appetite loss,
weakness and faintness
when arising from bed
or chair, constipation.
Rare:
- Sore throat, fever,
mouth sores; jaundice.
- Diminished sex drive,
numbness or tingling in
hands or feet.
Warnings & Precautions
Don't take if:
- You are allergic to any thiazide diuretic drug or prazosin.
- You are depressed.
- You will have surgery within 2 months, including dental
surgery, requiring general or spinal anesthesia.
Before you start, consult your doctor:
- If you are allergic to any sulfa drug.
- If you have gout, impaired circulation in brain or have had a
stroke, coronary heart disease (with or without angina), kidney
disease or impaired liver function.
- If you experience lightheadedness or fainting with other
antihypertensive drugs.
- If you are easily depressed.
Over age 60:
- Adverse reactions and side effects may be more frequent and
severe than in younger persons, especially dizziness and
excessive potassium loss.
- Don't stand while taking. Sudden changes in position may cause
falls. Sit or lie down promptly if you feel dizzy. If you have
impaired brain circulation or coronary heart disease, excessive
lowering of blood pressure should be avoided. Report problems to
your doctor immediately.
Pregnancy:
Risk to unborn child outweighs drug benefits. Don't use.
Breast-feeding:
Drug passes into milk. Avoid drug or discontinue nursing until
you finish medicine. Consult doctor for advice on maintaining
milk supply.
Infants & children:
Not recommended.
Prolonged use:
- You may need medicine to treat high blood pressure for the
rest of your life.
- Talk to your doctor about the need for follow-up medical
examinations or laboratory studies.
Skin & sunlight:
May cause rash or intensify sunburn in areas exposed to sun or
sunlamp.
Driving, piloting or hazardous work:
Don't drive or pilot aircraft until you learn how medicine
affects you. Don't work around dangerous machinery. Don't climb
ladders or work in high places. Danger increases if you drink
alcohol or take medicine affecting alertness and reflexes, such
as antihistamines, tranquilizers, sedatives, pain medicine,
narcotics and mind-altering drugs.
Discontinuing:
Don't discontinue without consulting doctor.
Others:
- First dose likely to cause fainting. Take it at night and get
out of bed slowly next morning.
- Hot weather and fever may cause dehydration and drop in blood
pressure. Dose may require temporary adjustment. Weigh daily and
report any unexpected weight decreases to your doctor.
- May cause rise in uric acid, leading to gout.
- May cause blood sugar rise in diabetics.
Possible Interaction with Other Drugs
GENERIC NAME |
COMBINED EFFECT |
| |
------------------------ |
----------------------- |
Acebutolol |
Increased antihypertensive effect. |
|
Dosages may require adjustments. |
ACE inhibitors*: |
Decreased blood pressure. |
| |
| |
Allopurinol |
Decreased allopurinol effect. |
Amphetamines* |
Decreased prazosin effect. |
Amphotericin B |
Increased potassium. |
Antidepressants, |
Dangerous drop in blood pressure. |
tricyclic (TCA)* |
Avoid combination unless under |
|
medical supervision. |
Antidiabetics*, other |
Increased blood sugar. |
Antihypertensives* |
Increased antihypertensive effect. |
|
Dosages may require adjustments. |
Barbiturates* |
Increased polythiazide effect. |
Carteolol |
Increased antihypertensive effect. |
Cholestyramine |
Decreased polythiazide effect. |
Chlorpromazine |
Acute agitation. |
Cortisone drugs* |
Excessive potassium loss that |
|
causes dangerous heart rhythms. |
Digitalis |
Excessive potassium loss that |
preparations* |
causes dangerous heart rhythms. |
Diuretics*, other |
Increased effect of other thiazide |
|
diuretics. |
Estrogens* |
Decreased prazosin effect. |
Indapamide |
Increased diuretic effect. |
Indomethacin |
Decreased polythiazide effect. |
Lithium |
Increased effect of lithium. |
MAO inhibitors* |
Blood pressure drop. Increased |
|
polythiazide effect. |
Nicardipine |
Blood pressure drop. Dosages may |
|
require adjustment. |
Nifedipine |
Weakness and faintness when arising |
|
from bed or chair. |
Nimodipine |
Dangerous blood pressure drop. |
Nitrates* |
Possible excessive blood pressure |
|
drop. |
Non-steroidal |
Decreased prazosin effect. |
| |
| |
Opiates* |
Weakness and faintness when arising |
|
from bed or chair. |
Potassium |
Decreased potassium effect. |
Probenecid |
Decreased probenecid effect. |
Sotalol |
Decreased antihypertensive effect. |
Sympathomimetics* |
Decreased prazosin effect. |
Terazosin |
Decreases effectiveness of |
|
terazosin. |
Verapamil |
Weakness and faintness when arising |
|
from bed or chair. |
Possible Interaction with Other Substances
INTERACTS WITH |
COMBINED EFFECT |
--------------- |
--------------- |
Alcohol: |
Dangerous blood pressure drop. |
|
Avoid. |
| |
Beverages: |
None expected. |
| |
Cocaine: |
Increased risk of heart block and |
|
high blood pressure. |
| |
| |
Licorice. |
Excessive potassium loss that |
|
causes dangerous heart rhythms. |
| |
Marijuana: |
Possible fainting, increased blood |
|
pressure. Avoid. |
| |
Tobacco: |
Possible spasm of coronary |
|
arteries. Avoid. |
|