Major
Hydrochlorothiazide × Losartan
Thiazide diuretics×Angiotensin II receptor blockers (sartans)
Mechanism
A thiazide diuretic plus an ARB synergistically lower blood pressure: the thiazide reduces circulating volume, losartan vasodilates by suppressing the RAAS. This is a target combination in hypertension and available as a fixed-dose product (losartan + hydrochlorothiazide).
Symptoms
Excessive blood pressure drop during titration: postural dizziness, syncope. Hypokalaemia and hyponatraemia from the thiazide, plus a mild rise in creatinine, can occur in the first weeks.
Management
The combination is a treatment standard. Doses are individualised, usually starting with losartan 50 mg + hydrochlorothiazide 12.5 mg/day. Check potassium, sodium, and creatinine 2–4 weeks after start, then annually.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Sources
- Lexicomp: Lexicomp Drug Interactions (2024)– Wolters Kluwer Clinical Drug Information, Inc. Lexi-Interact Online, 2024
- Pharmaceutical Press: Stockley's Drug Interactions, 12th edition (2024)– Preston CL (ed.). Stockley's Drug Interactions. 12th ed. London: Pharmaceutical Press; 2024