From the FDA Drug Label
In controlled clinical trials, discontinuation of therapy for adverse events occurred in 2. 3% of patients treated with losartan and 3. 7% of patients given placebo. In 4 clinical trials involving over 1000 patients on various doses (10 to 150 mg) of losartan potassium and over 300 patients given placebo, the adverse events that occurred in ≥2% of patients treated with losartan and more commonly than placebo were: dizziness (3% vs. 2%), upper respiratory infection (8% vs. 7%), nasal congestion (2% vs. 1%), and back pain (2% vs 1%). The following less common adverse reactions have been reported:
- Blood and Lymphatic System Disorders: Anemia.
- Psychiatric Disorders: Depression.
- Nervous System Disorders: Somnolence, headache, sleep disorders, paresthesia, migraine.
- Ear and Labyrinth Disorders: Vertigo, tinnitus.
- Cardiac Disorders: Palpitations, syncope, atrial fibrillation, CVA
- Respiratory, Thoracic and Mediastinal Disorders: Dyspnea.
- Gastrointestinal Disorders: Abdominal pain, constipation, nausea, vomiting.
- Skin and Subcutaneous Tissue Disorders: Urticaria, pruritus, rash, photosensitivity.
- Musculoskeletal and Connective Tissue Disorders: Myalgia, arthralgia.
- Reproductive System and Breast Disorders: Impotence
- General Disorders and Administration Site Conditions: Edema.
The side effects of Losartan include:
- Common side effects: dizziness, upper respiratory infection, nasal congestion, back pain
- Less common side effects: anemia, depression, somnolence, headache, sleep disorders, paresthesia, migraine, vertigo, tinnitus, palpitations, syncope, atrial fibrillation, CVA, dyspnea, abdominal pain, constipation, nausea, vomiting, urticaria, pruritus, rash, photosensitivity, myalgia, arthralgia, impotence, edema. 1
From the Research
Losartan can cause several side effects, including dizziness, lightheadedness, fatigue, and upper respiratory infections, with the most common side effect being dizziness, as reported in 2 and 3.
Common Side Effects
- Dizziness
- Lightheadedness
- Fatigue
- Upper respiratory infections like cough or cold symptoms
Less Common Side Effects
- Allergic reactions (rash, itching, swelling)
- Kidney problems
- Rarely, angioedema (severe swelling of face, lips, tongue, or throat)
Serious Side Effects
- Elevated potassium levels in the blood (hyperkalemia), particularly in patients with kidney problems or those taking potassium supplements or potassium-sparing diuretics
- Low blood pressure, especially when standing up quickly, which can cause dizziness or fainting
Tolerability
Losartan is generally well tolerated, with a similar incidence of cough to placebo, as reported in 2 and 3. The adverse effect profile of losartan is similar to that of placebo, with dizziness being the only drug-related event reported more frequently with losartan monotherapy than with placebo 2.
Recent Findings
A recent case report 4 suggests a possible association between losartan and tremors and dysarthria, although this is not a well-documented side effect.
Comparison with Other Medications
Losartan has been compared to other antihypertensive medications, such as amlodipine, and has been found to be better tolerated, with fewer clinical adverse experiences and discontinuations 5.
Overall
Losartan is a well-tolerated medication with a favorable side effect profile, making it a suitable option for the treatment of hypertension, as reported in 2, 3, and 6.