Losartan and Cough
Losartan rarely causes cough and is specifically recommended as the preferred alternative for patients who develop ACE inhibitor-induced cough. 1, 2
Incidence of Cough with Losartan
In patients with a history of ACE inhibitor-induced cough, losartan causes cough in only 17–36% of cases, compared to 62–87% with ACE inhibitors—a rate similar to placebo (26–35%) or hydrochlorothiazide (25%). 1, 3, 4, 5
The FDA label for losartan explicitly states that two prospective, randomized, controlled trials demonstrated that "the incidence of cough associated with losartan therapy, in a population that all had cough associated with ACE-inhibitor therapy, is similar to that associated with hydrochlorothiazide or placebo therapy." 3
Losartan does not inhibit angiotensin-converting enzyme and therefore does not cause accumulation of bradykinin or substance P—the mediators responsible for ACE inhibitor-induced cough. 2
Clinical Recommendation
The American College of Cardiology/American Heart Association provides a Class I, Level A recommendation (highest level) for switching to an ARB like losartan in patients who cannot tolerate ACE inhibitors due to cough. 1, 2
If a patient develops persistent dry cough while taking an ACE inhibitor, discontinue the ACE inhibitor immediately and substitute with losartan or another ARB. 1, 2
Cough from ACE inhibitors typically resolves within 1–4 weeks after discontinuation (median ~26 days), though some patients may require up to 3 months. 1, 2
Important Caveats
While extremely rare, isolated case reports exist of losartan-induced cough. 6 The FDA label acknowledges that "cases of cough, including positive re-challenges, have been reported with the use of losartan in postmarketing experience." 3
However, observational studies show that when cough occurs with losartan, 91% of patients had previously been prescribed an ACE inhibitor and 86% had previously experienced ACE inhibitor cough—indicating "carry-over" effects rather than true losartan-induced cough. 7
When reports of cough in the first week of losartan therapy are excluded (to eliminate carry-over from prior ACE inhibitor use), the rate of cough with losartan is 3–6 times lower than with ACE inhibitors. 7
Practical Management Algorithm
If a patient on an ACE inhibitor develops persistent dry cough, stop the ACE inhibitor immediately. 1, 2
Switch to losartan 50 mg once daily (or equivalent ARB dose). 8, 4, 5
Monitor for cough resolution over 1–4 weeks; if cough persists beyond 4 weeks, evaluate for alternative causes (GERD, asthma, post-nasal drip, heart failure-related pulmonary congestion). 1, 2
Check baseline renal function and potassium before starting losartan, then recheck within 1–2 weeks. 2
If the rare event of cough developing de novo with losartan occurs (without prior ACE inhibitor exposure), consider alternative diagnoses first before attributing it to losartan. 3, 7