Can losartan cause headaches? Unpacking a common side effect

October 9, 2025 •

4 min read

According to clinical trial data, headaches were among the most frequently reported adverse events in patients taking losartan, indicating that yes, losartan can cause headaches. This side effect is often temporary, typically occurring during the first week or two as the body adapts to the medication.

Quick Summary

Losartan is a common blood pressure medication that can cause mild, temporary headaches, particularly when a person first starts taking it. These headaches often improve as the body adjusts, and they are not unique to this specific class of medication.

Key Points

Initial Headaches are Common: Losartan can cause mild, temporary headaches, most often in the first one to two weeks of starting treatment as the body adjusts to lower blood pressure.
Not a Unique Side Effect: The incidence of headaches with losartan is similar to that of other ARBs and even some placebo groups, indicating it is not an unusual reaction.
Management is Possible: Strategies like staying hydrated, getting enough rest, and using doctor-approved OTC pain relievers can help alleviate headache symptoms.
Contact Your Doctor for Severe Symptoms: If headaches are severe, persistent beyond a couple of weeks, or accompanied by other serious side effects, medical consultation is essential.
Possible Vascular Changes: The reduction in blood pressure and changes in the body's vascular system caused by losartan are a likely reason for initial headaches.
Distinguish from Other Causes: Headaches can be triggered by stress, diet, or other medical conditions, so it's important to consider other potential causes.

Understanding the Link Between Losartan and Headaches

Losartan is an angiotensin II receptor blocker (ARB) primarily prescribed to treat high blood pressure (hypertension). While effective, it has a documented side effect profile, which includes the potential for headaches. For new users, experiencing a headache can be unsettling and raise concerns about the medication's suitability.

Is the Headache a Direct Result of Losartan?

Headaches are a known side effect of losartan, though their direct causation is complex. Clinical trials have shown that the incidence of headaches can sometimes be similar between patients taking losartan and those on a placebo. However, headaches are a recognized adverse event, and the shift in blood pressure caused by the medication is often the reason for the initial discomfort. For most patients, these headaches are mild, presenting as a tension-type headache. They are most common in the initial stages of treatment and typically resolve as the body acclimates. In extremely rare instances, losartan has been associated with severe migrainous headaches.

Potential Mechanisms Behind Losartan-Induced Headaches

While the exact mechanism is not fully understood, there are several hypotheses as to why losartan might cause headaches:

Vascular Adjustment: As losartan works to lower blood pressure, the body's blood vessels undergo changes in their diameter and pressure. This rapid vascular adjustment can trigger headaches in some individuals.
Central Nervous System Effects: Losartan's effect on the renin-angiotensin system can also impact blood flow in the brain, which may contribute to headache development.
Angiotensin II Regulation: Losartan blocks the angiotensin II receptor, which is crucial for blood pressure regulation. This blockade is the intended therapeutic effect but can lead to mild side effects like headaches and dizziness.

Managing Losartan-Related Headaches

If you experience headaches after starting losartan, there are several strategies you can employ to help manage the discomfort. Always consult your healthcare provider before starting any new treatment or making significant lifestyle changes, especially if your headaches are severe or do not improve.

Stay Well-Hydrated: Dehydration can exacerbate headaches. Drinking plenty of fluids throughout the day can help ease symptoms.
Ensure Adequate Rest: Getting a full night's sleep and incorporating rest periods into your daily routine can help reduce the frequency and severity of headaches.
Consider Over-the-Counter (OTC) Pain Relief: Mild pain relievers like acetaminophen (Tylenol) may be effective for managing headaches. However, it is crucial to speak with your doctor or pharmacist first, as some OTC medications, particularly NSAIDs like ibuprofen, can interfere with blood pressure regulation.
Limit Caffeine and Alcohol: Both caffeine and alcohol can affect blood pressure and may contribute to headaches. Reducing or eliminating them can be beneficial during the initial adjustment period.
Incorporate Stress-Reduction Techniques: High stress levels can be a headache trigger. Practicing mindfulness, meditation, or light exercise can help manage stress and potentially reduce headaches.

Losartan vs. Other Antihypertensive Medications

Headaches are not exclusive to losartan and are a known potential side effect across various types of blood pressure medications. Comparing losartan to other angiotensin II receptor blockers (ARBs) reveals that their side effect profiles are generally similar, with mild headaches and dizziness being common across the class.


Medication	Class	Common Side Effects (including headaches)	Notes	References
Losartan	ARB	Headache, dizziness, fatigue, upper respiratory infection	Side effects often improve with time; incidence is similar to other ARBs.	,
Valsartan	ARB	Headache, dizziness, fatigue, nausea, upper respiratory infection	Similar side effect profile to losartan.
Candesartan	ARB	Headache, dizziness, back pain, upper respiratory infection	Some studies show potential for fewer headaches than losartan.	,
Captopril	ACE Inhibitor	Headache, fatigue, cough	Headaches are a very common adverse event, similar to losartan.

Alternative Explanations for Headaches

It is important to consider that the headaches might not be directly caused by losartan. Headaches can stem from many other sources, including:

Pre-existing Conditions: Migraine-prone individuals may continue to experience headaches for other reasons.
Lifestyle Factors: Lack of sleep, poor diet, and stress are common headache triggers.
Other Medications: Headaches can also be a side effect of other drugs, so a review of all your medications with your doctor is prudent.

When to Contact Your Doctor

While mild, temporary headaches are a common part of adjusting to losartan, certain symptoms warrant a call to your healthcare provider. These include:

Severe or Persistent Headaches: If your headaches are severe or last longer than a week or two, you should inform your doctor.
New or Unusual Symptoms: If you experience other side effects, such as a severe migraine, swelling of the face or throat (angioedema), or chest pain, seek medical attention immediately.

Conclusion

Experiencing headaches after starting losartan is a common and often temporary side effect as your body adapts to the medication. While losartan can cause headaches, they are typically mild and manageable with lifestyle adjustments and, if necessary, OTC pain relief approved by your doctor. Monitoring your symptoms and communicating openly with your healthcare provider is crucial, especially if headaches are severe or do not resolve within a couple of weeks. For further information on losartan's side effects, please consult reputable sources like the National Health Service (NHS). Ultimately, the goal is to successfully manage your blood pressure while minimizing discomfort, which may involve your doctor adjusting your dosage or exploring alternative medications.

Frequently Asked Questions

For most people, headaches associated with losartan are temporary and subside within the first week or two as their body adapts to the medication.

If your headaches are persistent, severe, or last longer than a couple of weeks, you should contact your doctor. They may suggest a different medication or dosage.

It is best to consult your doctor or pharmacist before taking any OTC pain relievers. While acetaminophen is often safe, some medications like ibuprofen can affect your blood pressure.

No, a mild headache at the start of treatment can be a sign that the medication is actively working to lower your blood pressure. It is a normal part of the adjustment phase for many people.

Headaches can be a potential side effect of various blood pressure medications, not just losartan. The frequency can vary depending on the medication and individual.

Yes, headaches can be caused by numerous other factors, including stress, dehydration, or pre-existing conditions. Discussing all potential triggers with your doctor is important.

You should not stop taking losartan without first speaking to your doctor. Abruptly stopping blood pressure medication can be dangerous. Consult your healthcare provider about managing the side effect.