Can Losartan Cause Palpitations?
Yes, losartan can cause palpitations, though this is an uncommon adverse effect reported in post-marketing surveillance and clinical practice. 1
Evidence from FDA Drug Labeling
The FDA-approved prescribing information for losartan explicitly lists palpitations as a reported adverse reaction under "Cardiac Disorders," along with syncope, atrial fibrillation, and cerebrovascular accident. 1 This represents the highest quality evidence directly addressing your question, as it comes from comprehensive safety data collected across clinical trials and post-marketing surveillance.
Clinical Context and Frequency
In controlled clinical trials involving over 1,000 patients, the most common adverse events (≥2%) that occurred more frequently than placebo were dizziness (3% vs. 2%), upper respiratory infection (8% vs. 7%), nasal congestion (2% vs. 1%), and back pain (2% vs 1%). 1
Palpitations were reported as a less common adverse reaction (occurring in <2% of patients), but were documented frequently enough to warrant inclusion in the official prescribing information. 1
One case report documented a patient presenting with "occasional palpitations" along with severe hyponatremia after 3.5 months of losartan therapy, though the palpitations may have been secondary to the electrolyte disturbance rather than a direct drug effect. 2
Mechanism and Clinical Significance
Losartan's mechanism as an AT1 receptor antagonist does not typically produce direct cardiac rhythm disturbances, which distinguishes it from other cardiovascular medications. 3
In a study specifically evaluating arrhythmias in hypertensive men, losartan effectively controlled blood pressure and reduced left ventricular hypertrophy but did not alter the frequency or complexity of arrhythmias over 8 months of treatment. 4 This suggests that when palpitations occur, they are likely idiosyncratic rather than a class effect.
Comparison to Other Antihypertensive Agents
Losartan has a notably favorable cardiac tolerability profile compared to many other antihypertensive agents, particularly regarding symptomatic bradycardia or rhythm disturbances. 5, 1
The overall adverse event profile of losartan in clinical trials was similar to placebo, with discontinuation rates due to adverse events actually lower for losartan (2.3%) than placebo (3.7%). 1
Clinical Recommendations
If a patient reports palpitations on losartan, evaluate for other potential causes including electrolyte abnormalities (particularly hyponatremia and hyperkalemia), volume depletion, concurrent medications, or underlying cardiac conditions. 1, 2
Monitor serum electrolytes and renal function within 1-2 weeks of initiating losartan, as metabolic disturbances could manifest as palpitations. 6
Consider that palpitations may be unrelated to losartan given the low incidence in clinical trials and the drug's neutral effect on cardiac rhythm in controlled studies. 4