Reviewed on 3/30/2022

What Is Chlorothiazide and How Does It Work?

Chlorothiazide is a prescription medication used for the treatment of edema and symptoms of hypertension.

  • Chlorothiazide is available under the following different brand names: Diuril

What Are Dosages of Chlorothiazide?

Adult and pediatric dosage

Oral suspension

  • 250mg/5mL

Powder for injection

  • 500mg


  • 250mg
  • 500mg


Adult and geriatric dosage

  • 0.5-1 g (10 to 20 mL) orally/IV every day or every 12 hours; many patients with edema respond to intermittent therapy (ie, administration on alternate days or 3-5 days each week; reduces the risk of undesirable electrolyte imbalance)

Pediatric dosage

  • 10 to 20 mg/kg (5-10 mg/lb) every day or divided every 12 hours, not to exceed 375 mg/day


Adult and geriatric dosage

  • 0.5 -1 g (10-20 mL)/day orally/IV as single or divided dose; increase or decrease dosage based on blood pressure response

Pediatric dosage

  • 10 to 20 mg/kg (5-10 mg/lb) every day or divided every 12 hours, not to exceed 375 mg/day

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Chlorothiazide?

Common side effects of Chlorothiazide include:

Serious side effects of Chlorothiazide include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • fever,
  • sore throat,
  • burning eyes,
  • skin pain,
  • red or purple skin rash with blistering and peeling,
  • lightheadedness,
  • little or no urination,
  • severe pain in the upper stomach spreading to the back,
  • pale or yellowed skin,
  • dark-colored urine,
  • fever,
  • easy bruising or bleeding,
  • dry mouth,
  • increased thirst or urination,
  • confusion,
  • vomiting,
  • constipation,
  • muscle pain or weakness,
  • leg cramps,
  • dizziness,
  • drowsiness,
  • lack of energy,
  • restlessness,
  • fast heartbeats, and
  • tingly feeling.

Rare side effects of Chlorothiazide include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Chlorothiazide?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Chlorothiazide has severe interactions with no other drugs.
  • Chlorothiazide has serious interactions with the following drugs:
    • aminolevulinic acid oral
    • aminolevulinic acid topical
    • darolutamide
    • lofexidine
    • methyl aminolevulinate
    • squill
    • tretinoin
    • tretinoin topical
  • Chlorothiazide has moderate interactions with at least 164 other drugs.
  • Chlorothiazide has minor interactions with at least 145 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Chlorothiazide?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Chlorothiazide?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Chlorothiazide?”


  • May aggravate digitalis toxicity
  • Sensitivity reactions may occur with or without a history of allergy or asthma
  • Patients allergic to sulfa may show cross-sensitivity
  • May deleteriously alter lipid/glucose metabolism
  • Risk of male sexual dysfunction
  • Use with caution in severe renal disease. In patients with renal disease, thiazides may precipitate azotemia; cumulative effects of the drug may develop in patients with impaired renal function.
  • Thiazides should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte balance may precipitate hepatic coma
  • Thiazides may add to or potentiate the action of other antihypertensive drugs
  • Sensitivity reactions may occur in patients with or without a history of allergy or bronchial asthma; the possibility of exacerbation or activation of systemic lupus erythematosus has been reported
  • Lithium generally should not be given with diuretics
  • Although any chloride deficit is generally mild and usually does not require specific treatment except under extraordinary circumstances (as in liver disease or renal disease), chloride replacement may be required in the treatment of metabolic alkalosis
  • Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction, rather than administration of salt, except in rare instances when the hyponatremia is life-threatening; in actual salt depletion, appropriate replacement is the therapy of choice
  • Hyperuricemia may occur or acute gout may be precipitated in certain patients receiving thiazides
  • In diabetic patients dosage adjustments of insulin or oral hypoglycemic agents may be required; hyperglycemia may occur with thiazide diuretics; latent diabetes mellitus may become manifest during thiazide therapy
  • The antihypertensive effects of the drug may be enhanced in the post-sympathectomy patient
  • If progressive renal impairment becomes evident, consider withholding or discontinuing diuretic therapy;
  • Thiazides have been shown to increase the urinary excretion of magnesium; this may result in hypomagnesemia
  • Thiazides may decrease urinary calcium excretion; thiazides may cause intermittent and slight elevation of serum calcium in absence of known disorders of calcium metabolism; marked hypercalcemia may be evidence of hidden hyperparathyroidism; thiazides should be discontinued before carrying out tests for parathyroid function
  • Increases in cholesterol and triglyceride levels may be associated with thiazide diuretic therapy
  • Hypokalemia
    • Hypokalemia may develop, especially with brisk diuresis, when severe cirrhosis is present or after prolonged therapy; interference with adequate oral electrolyte intake will contribute to hypokalemia
    • Hypokalemia may cause cardiac arrhythmias and may also sensitize or exaggerate the response of the heart to toxic effects of digitalis (eg, increased ventricular irritability)
    • Hypokalemia may be avoided or treated by use of potassium-sparing diuretics or potassium supplements such as foods with a high potassium content
  • Electrolyte imbalance
    • All patients receiving diuretic therapy should be observed for evidence of fluid or electrolyte imbalance, including, hyponatremia, hypochloremic alkalosis, and hypokalemia
    • Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids
    • Warning signs or symptoms of fluid and electrolyte imbalance, irrespective of cause, include dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, confusion, seizures, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting

Pregnancy and Lactation

  • Use with caution if the benefits outweigh the risks during pregnancy
  • Use in LIFE-THREATENING emergencies when no safer drug is available. Positive evidence of human fetal risk.
  • Chlorothiazide may cause fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions which have occurred in the adult. Use of diuretics for pregnancy-induced hypertension should be avoided due to the risk of decreased placental perfusion
  • Lactation
    • Enters breast milk/not recommended (AAP states "compatible with nursing")

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