Common Side Effects of Losartan
The most common side effects of losartan are upper respiratory infections (8%), dizziness (3%), nasal congestion (2%), and back pain (2%), with these occurring more frequently than with placebo according to FDA data. 1
Frequency of Common Side Effects
Losartan is generally well-tolerated with an overall incidence of adverse events similar to placebo. According to the FDA drug label, the following side effects occur in ≥2% of patients treated with losartan and more commonly than with placebo:
- Upper respiratory infection: 8% (vs 7% with placebo)
- Dizziness: 3% (vs 2% with placebo)
- Nasal congestion: 2% (vs 1% with placebo)
- Back pain: 2% (vs 1% with placebo) 1
Less Common Side Effects
The FDA label also reports these less common adverse reactions:
- Blood and Lymphatic System: Anemia
- Psychiatric: Depression
- Nervous System: Somnolence, headache, sleep disorders, paresthesia, migraine
- Ear and Labyrinth: Vertigo, tinnitus
- Cardiac: Palpitations, syncope, atrial fibrillation, CVA
- Respiratory: Dyspnea
- Gastrointestinal: Abdominal pain, constipation, nausea, vomiting
- Skin: Urticaria, pruritus, rash, photosensitivity
- Musculoskeletal: Myalgia, arthralgia
- Reproductive System: Impotence
- General: Edema 1
Special Populations
Patients with Hypertension and Left Ventricular Hypertrophy
In the LIFE study, adverse reactions with losartan were similar to those reported for general hypertension patients. 1
Patients with Type 2 Diabetes and Nephropathy
In the RENAAL study, discontinuation rates due to side effects were similar between losartan and placebo (19% vs 24%). 1
Cough Comparison with ACE Inhibitors
One notable advantage of losartan over ACE inhibitors is the significantly lower incidence of cough:
- In controlled studies of patients who had experienced ACE inhibitor-induced cough:
- Losartan: 17-29% experienced cough
- Lisinopril (ACE inhibitor): 62-69% experienced cough
- Placebo/HCTZ: 25-35% experienced cough 1
This makes losartan a suitable alternative for patients who develop cough with ACE inhibitors.
Serious Side Effects to Monitor
While generally well-tolerated, patients should be monitored for:
- Hypotension, especially in volume-depleted patients
- Hyperkalemia (elevated potassium levels)
- Worsening renal function in patients with pre-existing kidney problems
- Allergic reactions including angioedema (rare but serious) 1
Pregnancy Considerations
Losartan is contraindicated in pregnancy as it can cause injury or death to the developing fetus, particularly when used in the second and third trimesters. 1
Clinical Implications
When prescribing losartan, clinicians should:
- Monitor blood pressure within 1-2 weeks after initiation or dose changes 2
- Monitor renal function and potassium levels, particularly in patients with pre-existing kidney disease 3
- Be aware that higher doses (up to 100 mg daily for hypertension or 150 mg daily for heart failure) may be needed for optimal outcomes 2
- Consider that losartan has a favorable drug interaction profile compared to many other antihypertensives 4
Losartan's generally favorable side effect profile makes it a good option for patients with hypertension, particularly those who cannot tolerate ACE inhibitors due to cough.