Can Losartan Cause Headaches, and How Common Is This Side Effect?

Yes, losartan can be associated with headaches, but they appear to be relatively common in both losartan and placebo groups in clinical trials, suggesting that many headaches may not be directly caused by the medication itself. ^[1] In large randomized, double‑blind studies involving about 2,900 people, headache was reported by 14.1% of those taking losartan compared with 17.2% of those taking placebo. This means headaches were slightly more frequent in people not receiving active treatment, indicating many are background symptoms. ^[1]

Authoritative consumer drug references list headache among more common or reported adverse effects, which aligns with trial data showing headache can occur during treatment. However, trial comparisons imply the majority of headaches may be unrelated to losartan. ^{[2] [3]} In FDA‑approved labeling summaries, headache is cataloged as a reported nervous system symptom, but not highlighted as a top differentiating side effect versus placebo. ^[4]

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How Common Is Headache With Losartan?

• In pooled double‑blind trials: Losartan 14.1% vs. placebo 17.2% for headache. This indicates headaches were common but not more frequent than with placebo. ^[1]
• Consumer drug monographs list headache among more common adverse effects observed with losartan use. These lists reflect reported events but do not prove causation. ^{[2] [3]}
• Labeling materials catalog headache under nervous system events, while side effects more clearly elevated over placebo include dizziness. Dizziness is one adverse effect that showed a drug‑related signal more than placebo. ^{[1] [4]}

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Context From Clinical Trials

In controlled comparisons, only dizziness was reported as “drug‑related” more often with losartan than placebo, while headache rates were actually higher on placebo. This pattern suggests losartan is generally well tolerated and does not strongly drive headache occurrence compared with background rates. ^[1] Overall discontinuations due to adverse effects were low and similar to placebo, supporting tolerability. These findings point to a favorable safety profile. ^[1]

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Practical Takeaways

• Headaches can occur while taking losartan, but they are common in the general population and were not more frequent than placebo in trials. ^[1]
• If you develop a new, severe, or persistent headache after starting losartan, monitor timing and severity, and consider other causes like dehydration, caffeine withdrawal, sinus issues, stress, or blood pressure changes. Seek medical advice if headaches worsen or are accompanied by warning signs (e.g., neurological symptoms). ^{[2] [3]}
• Because losartan lowers blood pressure, a sudden drop can occasionally lead to symptoms like dizziness and less commonly headache, especially after dose changes; discussing dose timing and blood pressure readings can help. Dizziness showed a clearer association with losartan than headache in trials. ^[1]

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Summary Table: Headache Reporting With Losartan

Source	Group	Headache Frequency/Status	Key Interpretation
Double‑blind trials (≈2,900 participants) [1]	Losartan	14.1%	Common event, but not higher than placebo
Double‑blind trials (≈2,900 participants) [1]	Placebo	17.2%	Headache slightly more frequent than with losartan
Consumer monograph [2]	Losartan	Listed among more common side effects	Reported clinically; causation not certain
Consumer monograph (incidence not specified) [3]	Losartan	Headache included among reported events	Catalog of observed symptoms
Labeling overview [4]	Losartan	Headache listed under nervous system events	Not highlighted as more common than placebo

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When to Contact a Clinician

• Severe, sudden, “worst headache of life,” or headache with neurological symptoms (weakness, confusion, vision changes). Immediate evaluation is important for these red flags. ^[2]
• Headaches that persist beyond a few days, significantly interfere with daily activities, or start after dose changes review blood pressure readings and hydration and consult your clinician for adjustments. This helps distinguish medication effects from other causes. ^{[1] [2]}

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Bottom Line

Losartan can be associated with headaches, but in well‑controlled studies headaches were slightly more common with placebo than with losartan, suggesting many headaches during therapy may not be caused by the drug itself. ^[1] Headache is nonetheless a recognized reported symptom in consumer drug resources, so it’s reasonable to monitor and discuss with your clinician if headaches are persistent or severe. Overall, losartan demonstrates strong tolerability, with dizziness showing a clearer medication‑related signal than headache. ^{[1] [2] [4]}