Applies to chlorothiazide: oral suspension, oral tablet. Other dosage forms:

• intravenous powder for solution

Serious side effects of Chlorothiazide

Along with its needed effects, chlorothiazide 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 while taking chlorothiazide:

Incidence not known

• Abdominal or stomach pain
• back, leg, or stomach pains
• black, tarry stools
• bleeding gums
• blistering, peeling, or loosening of skin
• bloating
• blood in 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 swallowing
• dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
• 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 hands or feet
• pain in joints or muscles
• painful or difficult urination
• pains in stomach, side, or abdomen, possibly radiating to the back
• pale skin
• pinpoint red spots on 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 lips or in mouth
• sores, welting, or blisters
• sugar in the urine
• swelling of face, fingers, legs, ankles, feet, or lower legs
• swollen or painful glands
• tenderness of salivary glands
• thickening of bronchial secretions
• tightness in 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 legs
• weight gain
• wheezing
• yellow eyes or skin

Other side effects of Chlorothiazide

Some side effects of chlorothiazide 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, thinning of hair
• inability to have or keep an erection
• increased sensitivity of skin to sunlight
• loss in sexual ability, desire, drive, or performance
• muscle spasm
• pinpoint red or purple spots on skin
• redness or other discoloration of skin
• restlessness
• sensation of spinning
• severe sunburn
• weakness

For Healthcare Professionals

Applies to chlorothiazide: intravenous powder for injection, oral suspension, oral tablet.

Metabolic

Metabolic changes associated with chlorothiazide, as with other thiazide diuretics, are relatively common, especially when daily doses greater than 500 mg are used. Mild hypokalemia (decrease of 0.5 mEq/L) occurs in up to 50%, and may predispose patients to cardiac arrhythmias. Metabolic alkalosis, hyponatremia, hypomagnesemia, hypophosphatemia, hypercalcemia, hyperglycemia, hypercholesterolemia, and hyperuricemia are also relatively common.^[Ref]

Hyperuricemia may be an important consideration in patients with a history of gout. Hypophosphatemia and low serum magnesium concentrations may occur, but are usually clinically insignificant except in malnourished patients.

Rare cases of the milk-alkali syndrome (hypercalcemia, metabolic alkalosis, and renal insufficiency) have been associated with chlorothiazide.

Chlorothiazide-induced hypercalcemia appears to depend on circulating parathyroid hormone.^[Ref]

Cardiovascular

Cardiovascular complications of diuretic therapy include orthostatic hypotension secondary to intravascular volume depletion. This has resulted in syncope and, in some patients with glaucoma, temporary loss of vision. Rare cases of cerebrovascular accident associated with thiazide-induced diuresis have been reported.^[Ref]

Hypersensitivity

Hypersensitivity reactions usually involve the skin (cutaneous vasculitis, urticaria, rash, purpura), but may involve the gastrointestinal system (nausea, vomiting, or diarrhea), the genitourinary system (interstitial nephritis), and the respiratory system (acute noncardiogenic pulmonary edema, pneumonitis). Thiazide diuretics may induce phototoxic dermatitis.^[Ref]

Thiazides may induce allergic reactions in patients who are allergic to sulfonamides.^[Ref]

Dermatologic

Dermatologic reactions may indicate hypersensitivity to the drug. Erythema multiforme, Stevens-Johnson syndrome, exfoliative dermatitis (including toxic epidermal necrolysis), and alopecia have been reported in rare cases.^[Ref]

Gastrointestinal

A retrospective case-control drug surveillance study has revealed the relative risk of acute cholecystitis associated with the use of a thiazide diuretic is 2.0. The suspected explanation for this association is the potentially deleterious effect thiazides have on the serum lipid profile. Chlorothiazide-induced hypercholesterolemia or hypertriglyceridemia may enhance the formation of some types of gallstones.^[Ref]

Gastrointestinal problems include diarrhea, vomiting, constipation or abdominal pain in approximately 5% of patients. Thiazide diuretics have been associated with acute cholecystitis and rare cases of pancreatitis.^[Ref]

Renal

Renal side effects including new or worsened renal insufficiency associated with chlorothiazide therapy is a probable sign of intravascular volume depletion, and serves as a signal to reduce or withhold therapy. Rare cases of allergic interstitial nephritis have been associated with chlorothiazide.^[Ref]

Endocrine

Endocrinologic changes associated with chlorothiazide, as with other thiazide diuretic agents, include decreased glucose tolerance and a potentially deleterious effect on the lipid profile. This may be important in some patients with or who are at risk for diabetes or coronary artery disease.^[Ref]

Hematologic

Hematologic side effects are rare. Rare cases of immune-complex hemolytic anemia, aplastic anemia, and thrombocytopenia have been associated with thiazide diuretics.^[Ref]

Musculoskeletal

Musculoskeletal cramping or spasms have occasionally been reported during chlorothiazide diuresis.^[Ref]

Genitourinary

Genitourinary problems have been limited to rare complaints of impotence among male patients.^[Ref]