Hydrochlorothiazide
Also known as: HydroDIURIL, Microzide, Aldactazide, Hydro-Par, Ezide, Co-amilozide, Moduret, Moduretic
**Hydrochlorothiazide (HCTZ)** is a "water pill" (diuretic) used to treat fluid retention, high blood pressure, certain types of kidney stones (calcium oxalate), and a specific water-balance disorder called diabetes insipidus. * **Increased Urination**: Your pet will likely urinate more frequently and in larger amounts. Ensure they always have access to fresh, clean drinking water unless your veterinarian has specifically restricted it. * **Bathroom Breaks**: Dogs will need to be let outside more often to prevent indoor accidents. Ensure litter boxes are kept clean for cats. * **Watch for Imbalances**: Because this drug removes water and salts from the body, watch for signs of dehydration or low potassium. Contact your veterinarian immediately if you notice: * Excessive thirst or extreme lethargy/weakness * Restlessness or confusion * Vomiting or diarrhea (which can worsen fluid loss) * A sudden decrease in urination * **Give with Food**: If the medication upsets your pet's stomach, try giving it with a small meal or treat. * **Do Not Stop Abruptly**: If treating heart failure or high blood pressure, do not stop giving this medication without consulting your veterinarian, as symptoms can rapidly return.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Treatment of systemic hypertension
- Treatment of systemic hypertension
- Diuretic for heart failure
- Ascites in patients with liver disease
- To reduce calcium oxalate saturation in urine
- Refractory congestive heart failure / Calcium oxalate urolithiasis prevention / Hypertension
- Adjunctive therapy of hyperkalemic periodic paralysis (HyPP)
- Treatment of nephrogenic diabetes insipidus
- Treatment of nephrogenic diabetes insipidus
- Treatment of systemic hypertension
- Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria
- Prevention of recurrent calcium oxalate uroliths with renal hypercalcuria
How it is given
Possible side effects
- Hypokalemia (most common)
- Hypochloremic alkalosis
- Dilutional hyponatremia
- Hypomagnesemia
- Hypercalcemia (hyperparathyroid-like effects)
- Hypophosphatemia
- Hyperuricemia
- Gastrointestinal reactions (vomiting, diarrhea)
- Polyuria
- Hyperglycemia
- Hyperlipidemias
- Orthostatic hypotension
- Hypersensitivity/dermatologic reactions
- Hypokalaemia
Cautions & contraindications
- Hypersensitivity to thiazides or sulfonamides
- Anuria
- Pregnancy (relative contraindication in otherwise healthy patients with mild edema)
- Dogs with absorptive (intestinal) hypercalciuria (may result in hypercalcemia)
- Renal impairment (due to reduction in GFR)
- Severe electrolyte imbalances (e.g., severe hypokalaemia or hyponatraemia)
- **Extreme Caution/Avoid**: Severe renal disease, preexisting electrolyte (including hypercalcemia) or water balance abnormalities, impaired hepatic function (may precipitate hepatic coma), hyperuricemia, systemic lupus erythematosus (SLE), or diabetes mellitus. **Monitoring**: Patients with conditions that may lead to electrolyte or water balance abnormalities (e.g., vomiting, diarrhea) should be monitored carefully. Chronic therapy requires monitoring of serum potassium. **Laboratory Test Interferences**: May increase serum amylase, decrease renal excretion of cortisol, falsely decrease total urinary estrogen, cause false-negative histamine tests for pheochromocytoma, elevate serum calcium (discontinue prior to parathyroid testing), compete for PSP secretion, cause false-negative phentolamine tests, decrease protein-bound iodine, slightly reduce T3 resin uptake, and cause false-negative tyramine tests.
Drug interactions
- Amphotericin B: Increased risk for severe hypokalemia
- Corticosteroids, Corticotropin: Increased risk for severe hypokalemia
- Diazoxide: Increased risk for hyperglycemia, hyperuricemia, and hypotension
- Digoxin: Thiazide-induced hypokalemia, hypomagnesemia, and/or hypercalcemia may increase the likelihood of digitalis toxicity
- Insulin: Thiazides may increase insulin requirements
- Lithium: Thiazides can increase serum lithium concentrations
- Methenamine: Thiazides can alkalinize urine and reduce methenamine effectiveness
- NSAIDs: Thiazides may increase risk for renal toxicity and NSAIDs may reduce diuretic actions of thiazides
- Neuromuscular Blocking Agents: Tubocurarine or other nondepolarizing neuromuscular blocking agents response or duration of effect may be increased
- Probenecid: Blocks thiazide-induced uric acid retention (used to therapeutic advantage)
- Quinidine: Half-life may be prolonged by thiazides (thiazides can alkalinize the urine)
Frequently asked questions
What is Hydrochlorothiazide used for in pets?
**Hydrochlorothiazide (HCTZ)** is a "water pill" (diuretic) used to treat fluid retention, high blood pressure, certain types of kidney stones (calcium oxalate), and a specific water-balance disorder called diabetes insipidus. * **Increased Urination**: Your pet will likely urinate more frequently and in larger amounts. Ensure they always have access to fresh, clean drinking water unless your veterinarian has specifically restricted it. * **Bathroom Breaks**: Dogs will need to be let outside more often to prevent indoor accidents. Ensure litter boxes are kept clean for cats. * **Watch for Imbalances**: Because this drug removes water and salts from the body, watch for signs of dehydration or low potassium. Contact your veterinarian immediately if you notice: * Excessive thirst or extreme lethargy/weakness * Restlessness or confusion * Vomiting or diarrhea (which can worsen fluid loss) * A sudden decrease in urination * **Give with Food**: If the medication upsets your pet's stomach, try giving it with a small meal or treat. * **Do Not Stop Abruptly**: If treating heart failure or high blood pressure, do not stop giving this medication without consulting your veterinarian, as symptoms can rapidly return.
Is Hydrochlorothiazide safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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