What are the common side effects of olmesartan (angiotensin II receptor antagonist)?

Most Common Side Effects of Olmesartan

The most common side effect of olmesartan is dizziness, occurring in approximately 3% of patients compared to 1% in placebo groups, according to FDA clinical trial data. 1

Common Side Effects

Frequently Reported Side Effects

• Dizziness (3%) - most common adverse reaction reported in clinical trials 1
• Headache - reported in up to 5.4% of patients 2
• Gastrointestinal disorders - reported in up to 10% of patients 2
• Upper respiratory tract infections - reported in up to 7.1% of patients 2

Metabolic and Laboratory Abnormalities

• Hyperkalemia - can occur due to olmesartan's effect on the renin-angiotensin system 1
• Elevated creatinine levels - particularly in patients with renal impairment 1

Rare but Serious Side Effects

Sprue-Like Enteropathy

• Characterized by severe chronic diarrhea with substantial weight loss
• Can occur months to years after starting olmesartan
• Intestinal biopsies often show villous atrophy
• Symptoms resolve after discontinuation of the medication 1, 3

Photosensitivity

• Olmesartan is among the angiotensin receptor blockers that can cause photosensitive reactions
• May present as exaggerated sunburn reactions or dermatitis 4

Cardiovascular Effects

• Hypotension may occur, especially in volume- or salt-depleted patients 1
• Risk of increased cardiovascular mortality in diabetic patients taking high-dose olmesartan (40 mg/day) for >6 months 1

Pregnancy-Related Effects

• Contraindicated during pregnancy due to fetal toxicity
• Can cause fetal harm when used during second and third trimesters
• May result in oligohydramnios, fetal lung hypoplasia, and skeletal deformations 1, 5

Monitoring Recommendations

1. Blood pressure - assess response within 2 weeks after initiation or dose adjustment 5
2. Renal function - monitor creatinine and BUN, especially in patients with:
   • Severe heart failure
   • Renal artery stenosis
   • Volume depletion 1
3. Potassium levels - particularly in patients with:
   • Chronic kidney disease
   • Taking potassium supplements
   • Taking potassium-sparing medications 5, 1

Clinical Considerations

• Olmesartan has a favorable safety profile with discontinuation rates due to adverse events similar to placebo (2.4% vs 2.7%) 1
• The incidence of adverse effects does not appear to be dose-dependent within the therapeutic range 1
• Olmesartan should be used with caution in patients with bilateral renal artery stenosis due to risk of acute renal failure 5
• Avoid combining olmesartan with ACE inhibitors or direct renin inhibitors due to increased risk of adverse effects 5

Practical Management of Side Effects

• For dizziness: Advise patients to rise slowly from sitting or lying positions
• For hypotension: Place patient in supine position and consider IV normal saline if needed 1
• For suspected sprue-like enteropathy: Discontinue olmesartan and consider alternative antihypertensive therapy 1
• For photosensitivity: Advise patients to use sunscreen, wear protective clothing, and avoid midday sun exposure 4

Remember that while olmesartan is generally well-tolerated, recognizing and managing these side effects promptly can improve patient adherence and outcomes.