Combining Losartan and Maxzide: Not Recommended
The combination of losartan and Maxzide (triamterene/hydrochlorothiazide) should generally be avoided due to the significant risk of hyperkalemia from combining an ARB with a potassium-sparing diuretic. If blood pressure control requires both an ARB and a diuretic, use losartan with hydrochlorothiazide alone (without triamterene) instead.
Why This Combination Is Problematic
Hyperkalemia Risk
Losartan (an ARB) increases serum potassium by blocking aldosterone-mediated potassium excretion in the kidneys 1.
Triamterene is a potassium-sparing diuretic that directly blocks potassium secretion in the distal tubule 1.
The FDA label for losartan explicitly warns that coadministration with drugs that raise serum potassium (including potassium-sparing diuretics) may result in hyperkalemia and requires monitoring 2.
The FDA label for triamterene states it should not be given with other potassium-sparing agents, and specifically warns against combining it with medications that elevate potassium 3.
Additional Concerns
Patients with chronic kidney disease (CKD) face amplified risk, as both ARBs and potassium-sparing diuretics carry increased hyperkalemia risk when GFR is reduced 1, 2.
The 2017 ACC/AHA guidelines recommend avoiding potassium-sparing diuretics in patients with significant CKD (GFR <45 mL/min), which overlaps with the population often prescribed ARBs 1.
The Preferred Alternative
Losartan Plus Hydrochlorothiazide (Without Triamterene)
ARBs combined with thiazide diuretics (not potassium-sparing) are well-established, effective, and safe combinations for hypertension management 1.
Losartan combined with hydrochlorothiazide provides complementary mechanisms: the thiazide may stimulate the renin-angiotensin-aldosterone system, which the ARB then blocks, resulting in additive blood pressure lowering 1.
Multiple studies demonstrate superior blood pressure control and renoprotection with losartan-hydrochlorothiazide combinations compared to losartan monotherapy 4, 5, 6.
Fixed-dose combinations of losartan/hydrochlorothiazide are widely available (e.g., Hyzaar 50/12.5 mg or 100/25 mg), improving adherence 1, 4.
Clinical Management If This Combination Is Encountered
If a Patient Is Already Taking Both
Check serum potassium immediately and monitor closely for hyperkalemia 2.
Assess renal function (serum creatinine, GFR) as impaired kidney function magnifies risk 1, 2.
Consider switching from Maxzide to hydrochlorothiazide alone (without triamterene) while continuing losartan 1.
If potassium levels are elevated or the patient has CKD, discontinue the potassium-sparing component immediately 2, 3.
Monitoring Parameters
Serum potassium should be checked within 1-2 weeks of initiating or changing therapy, then periodically thereafter 2.
Renal function monitoring is essential, particularly in elderly patients, those with diabetes, or baseline kidney disease 2, 5.
Avoid potassium supplements or salt substitutes containing potassium in patients on this combination 3.
Common Pitfalls to Avoid
Do not assume the hydrochlorothiazide component of Maxzide negates the potassium-sparing effect of triamterene—both components remain active 3, 7.
Do not overlook drug-drug interactions: NSAIDs, ACE inhibitors, or other agents affecting potassium further increase risk when combined with this regimen 2.
Recognize that older patients and those with diabetes are at higher baseline risk for both hyperkalemia and renal dysfunction 1, 2, 5.