What are the side effects of Singulair (montelukast)?

A number of side effects may occur when using Singulair (montelukast). Contact your doctor if any of the following side effects are particularly severe: lightheadedness, heartburn, fatigue, stomach pain or headaches.

If you experience any of the following symptoms, contact your doctor immediately: rash, fever, hives, numbness, painful or swollen sinuses, flu-like symptoms, itching, hoarseness, breathing problems or swelling in any area of the body, such as the face, legs or hands.

Although far less common, Singulair may also cause certain mental health changes, such as strange dreams, hallucinations, anxiety or suicidal thoughts. Discuss such symptoms with your doctor immediately.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.