Allopurinol
Severe
Textbook
Hypersensitivity reactions reported in patients with compromised renal function.
Source: G&G 14e · p849
Drug reference
methyclothiazide
Thiazide Diuretic · Diuretic
Thiazide DiureticDiuretic
CDSCO approved
EXCRETION
—
not curated
INTERACTIONS
1 major
SEVERE in our sources
PREGNANCY
—
not curated
Top interactionssee all 12 →
- AllopurinolSevereTextbookG&G 14e · p849
Mechanism
Methyclothiazide inhibits NaCl transport in the distal convoluted tubule by blocking the Na+-Cl− symporter (ENCC1 or TSC) on the luminal membrane of DCT epithelial cells. Some thiazide diuretics also weakly inhibit carbonic anhydrase.
Indications
edema associated with diseases of the heart (CHF)edema associated with diseases of the liver (hepatic cirrhosis)edema associated with diseases of the kidney (nephrotic syndrome, chronic renal failure, acute glomerulonephritis)hypertensionCa2+ nephrolithiasisosteoporosisnephrogenic diabetes insipidusBr− intoxication
Pharmacokinetics
Half-life
ID
Bioavailability
ID
Metabolism
M
Contraindications
- hypersensitive to sulfonamides
Side effects
Common
vertigoheadachephotosensitivityskin rasheserectile dysfunctionhypokalemiahyperuricemiadecreased glucose toleranceincreased plasma LDL cholesterolincreased plasma total cholesterolincreased plasma total triglycerides
Serious
- systemic lupus erythematosus
- sulfa allergic reactions
- extracellular volume depletion
- hypotension
- hyponatremia (severe, potentially fatal)
- hypochloremia
- metabolic alkalosis
- hypomagnesemia
- hypercalcemia
- unmask latent diabetes mellitus
Drug interactions
Aceclofenac + Paracetamol
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Aceclofenac
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Amiloride
Moderate
Textbook
Reduced K+ loss and risk of ventricular arrhythmias from thiazides. However, combining K+-sparing agents with each other or with K+ supplementation requires great caution.
This combination is effective for preventing hypokalemia. Use great caution and monitor K+ if combining multiple K+-sparing agents or supplements.
Source: G&G 14e
Aspirin
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Bromfenac
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Capsaicin
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Cholestyramine
Moderate
Textbook
Reduced efficacy of thiazides.
Patients should take other medications 1 h before or 3 to 4 h after a dose of cholestyramine.
Source: G&G 14e · p738
Choline Salicylate
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Colestipol
Moderate
Textbook
Reduced efficacy of thiazides.
Patients should take other medications 1 h before or 3 to 4 h after a dose of colestipol.
Source: G&G 14e · p738
Corticosteroids
Moderate
Textbook
Can amplify the hypokalemia produced by diuretics.
Monitor K+ levels closely.
Source: G&G 14e
Diclofenac + Paracetamol
Moderate
Textbook
Reduce the antihypertensive effects of diuretics (and all other antihypertensives).
Be aware of reduced efficacy of thiazides when combined with NSAIDs.
Source: G&G 14e
Related guidelines
Other Thiazide Diuretic drugs
Ask House about methyclothiazide
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: Goodman & Gilman 14e·Verified: 2026-05-10 · House clinical team