Can loss of taste or smell occur after initiating losartan therapy?

Loss of Taste or Smell with Losartan

Loss of taste or smell can occur with losartan, though it is uncommon and occurs at rates similar to placebo in most clinical trials.

Evidence from Clinical Trials and FDA Labeling

The FDA label for losartan does not list anosmia (loss of smell) or ageusia (loss of taste) as reported adverse events in the standard safety profile 1. In controlled clinical trials of over 1000 patients on losartan versus 300 on placebo, taste disturbances were not among the adverse events occurring in ≥2% of patients 1.

However, a direct comparative study in healthy volunteers demonstrated that losartan does cause measurable taste disturbances 2. This randomized, placebo-controlled crossover trial found that:

• Detection thresholds for all four basic tastes (sweet, salty, sour, bitter) were significantly worsened with losartan compared to baseline 2
• The degree of taste alteration with losartan was similar to that seen with the ACE inhibitor perindopril 2
• Importantly, no subjects subjectively complained of taste disturbance despite objective testing showing impairment 2

This explains the apparent discrepancy—the effect exists but may be subclinical or not bothersome enough for patients to report spontaneously.

Mechanism and Clinical Context

The taste disturbance mechanism with losartan differs from ACE inhibitors 2. While ACE inhibitors cause taste changes through bradykinin and substance P accumulation, losartan's mechanism remains unclear but appears related to renin-angiotensin system modulation 2.

Importantly, losartan was specifically developed as an alternative for patients who develop cough with ACE inhibitors, and multiple guidelines recommend this switch 3, 4. The incidence of cough with losartan is similar to placebo (17-29%) versus ACE inhibitors (62-69%) in patients with prior ACE inhibitor-induced cough 1.

Clinical Recommendations

If your patient reports new loss of taste or smell after starting losartan:

• Consider this a possible medication side effect, though uncommon 2

• Rule out other causes, particularly:

  • Recent viral upper respiratory infection (which commonly causes anosmia) 5
  • Other medications the patient may be taking
  • Nasal/sinus pathology 5

• If symptoms are bothersome and no other cause is identified, consider switching to an alternative antihypertensive class such as:

  • Calcium channel blockers 4, 6
  • Thiazide diuretics 6
  • Beta-blockers (if appropriate for the patient's comorbidities) 4

• Do not switch back to an ACE inhibitor if the patient previously had ACE inhibitor-induced cough, as this was likely the reason for the losartan switch 3, 4

Important Caveats

• The symptom timing is critical—if loss of smell/taste occurred during the COVID-19 pandemic era or with any concurrent respiratory symptoms, viral infection is far more likely than medication effect 5
• Losartan should be continued for established cardiovascular indications (heart failure, post-MI, diabetic nephropathy) unless the side effect is truly intolerable, as the cardiovascular benefits are substantial 4, 7, 6
• Monitor for other losartan-related adverse effects including dizziness, hyperkalemia, and renal function changes 1