Can losartan potassium 50 mg daily cause swollen ankles?

The short version: losartan is not a typical cause of ankle swelling, but it can cause it in a few specific ways, and one of them is a medical emergency.

Losartan is an ARB, a blood pressure drug. The retrieved records show its common side effects are upper respiratory infection, dizziness, back pain and nasal congestion, not edema [3]. The classic ARB/ACE-inhibitor swelling problem is angioedema, a deeper swelling of lips, tongue or throat, and losartan raises bradykinin, the peptide behind that risk [2]. Angioedema can involve the face and airway, not just the ankles. If swelling comes with lip, tongue or throat swelling or trouble breathing, that is an emergency, not a wait-and-see.

Ankle swelling on losartan usually has another driver. Kidney problems, heart failure, or a second drug like amlodipine are far more common causes. Amlodipine causes dose-dependent ankle edema: 7.5% at 2.5 mg, 13.75% at 5 mg, 28.75% at 10 mg [1]. If you take both, the amlodipine is the likelier culprit.

The retrieval did not surface a losartan-specific edema trial. That gap is real. What it does show: losartan can affect kidney function and potassium handling [4, 5], and kidney problems can cause fluid retention. So the honest answer is that losartan is an uncommon direct cause, but worth checking if swelling is new, one-sided, or comes with breathlessness.

My call: possible but uncommon; check amlodipine, kidney function, and heart failure first, and treat any lip or throat swelling as urgent. Confidence: moderate.