Hydrochlorothiazide is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Hydrochlorothiazide is also used to treat fluid retention (edema) that is caused by congestive heart failure, severe liver disease (cirrhosis), kidney disease, or treatment with a steroid or hormone medicine.

Hydrochlorothiazide is a thiazide diuretic (water pill). It is used to help reduce the amount of water in the body by increasing the flow of urine. It may also be used for other conditions as determined by your doctor.

This medicine is available only with your doctor's prescription.

In addition to the use of this medicine, treatment for your high blood pressure may include weight control and changes in the types of foods you eat, especially foods high in sodium (salt) or potassium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.

Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.

Remember that this medicine will not cure your high blood pressure, but it does help control it. You must continue to receive it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Incidence not known

Abdominal or stomach pain

back, leg, or stomach pains

black, tarry stools

bleeding gums

blistering, peeling, or loosening of the skin

bloating

blood in the urine or stools

bloody urine

blue lips and fingernails

blurred vision

burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings

chest pain

chills

clay-colored stools

cloudy urine

cold sweats

confusion

constipation

cough or hoarseness

coughing that sometimes produces a pink frothy sputum

coughing up blood

cracks in the skin

darkened urine

decrease in urine output or decrease in urine-concentrating ability

decreased frequency or amount of urine

diarrhea

difficult, fast, or noisy breathing, sometimes with wheezing

difficulty with breathing

difficulty with swallowing

dizziness, faintness, or lightheadedness when getting up from a lying or sitting position

dry mouth

fast or irregular heartbeat

fever

flushed, dry skin

fruit-like breath odor

general body swelling

general feeling of discomfort or illness

general feeling of tiredness or weakness

greatly decreased frequency of urination or amount of urine

headache

hives

increased blood pressure

increased hunger

increased sweating

increased thirst

increased urination

indigestion

itching

joint pain, stiffness, or swelling

loss of appetite

loss of heat from the body

lower back or side pain

muscle cramps or pain

nausea or vomiting

nosebleeds

numbness, tingling, pain, or weakness in the hands or feet

pain in the joints or muscles

painful or difficult urination

pains in the stomach, side, or abdomen, possibly radiating to the back

pale skin

pinpoint red spots on the skin

puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue

rash

red, irritated eyes

red skin lesions, often with a purple center

red, swollen skin

redness, soreness, or itching skin

scaly skin

seizures

shortness of breath

sore throat

sores, ulcers, or white spots on the lips or in the mouth

sores, welting, or blisters

sugar in the urine

swelling of the face, fingers, legs, ankles, feet, or lower legs

swollen or painful glands

tenderness of salivary glands

thickening of bronchial secretions

tightness in the chest

trembling

troubled breathing

unpleasant breath odor

unusual bleeding or bruising

unusual tiredness or weakness

unusual weight loss

vomiting of blood

weakness and heaviness of the legs

weight gain

wheezing

yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

Cramping

decreased interest in sexual intercourse

difficulty having a bowel movement (stool)

feeling of constant movement of self or surroundings

hair loss or thinning of the hair

inability to have or keep an erection

increased sensitivity of the skin to sunlight

loss in sexual ability, desire, drive, or performance

muscle spasm

pinpoint red or purple spots on the skin

redness or other discoloration of the skin

restlessness

sensation of spinning

severe sunburn

weakness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Check with your doctor right away if you have any of the following symptoms while taking this medicine: convulsions or seizures; decreased urine; drowsiness; dry mouth; excessive thirst; increased heart rate or pulse; muscle pains or cramps; nausea or vomiting; or unusual tiredness or weakness. These may be symptoms of a condition called hypokalemia or potassium loss.

Stop using this medicine and check with your doctor immediately if you have blurred vision, difficulty in reading, eye pain, or any other change in vision during or after treatment. This could be a sign of a serious eye problem. Your doctor will want you to have your eyes checked by an ophthalmologist (eye doctor).

This medicine may cause some people to become dizzy. Do not drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.

Drinking alcoholic beverages may also make the dizziness worse. While you are taking this medicine, be careful to limit the amount of alcohol you drink.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests (e.g., tests for parathyroid function) may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.