What side effects can this medication cause?

Montelukast may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• dizziness
• heartburn
• stomach pain
• tiredness

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

• difficulty breathing or swallowing
• swelling of the face, throat, tongue, lips, eyes, hands, feet, ankles, or lower legs
• hoarseness
• itching
• rash
• hives
• fever
• flu-like symptoms
• pins and needles or numbness in the arms or legs
• pain and swelling of the sinuses

Montelukast may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.