What are Singulair (montelukast) side effects?

Seek emergency medical care immediately if you experience any of the following symptoms - they are signs of an allergic reaction that can be life-threatening if left untreated: difficulty breathing, hives, severe itchiness, swelling of face, throat, lips, and tongue

Some of the common side effects of Singulair include:

• Headache
• Heartburn
• Stomachache
• Fatigue
• Fever
• Dizziness
• Diarrhea
• Cold and flu symptoms 

These Singulair side effects do not usually require medical attention; however, you should report them to your prescribing physician if they are severe or do not go away over time. 

Some potential side effects of Singulair are more serious and require medical attention. You should inform your doctor without delay if you experience:

• Rash, hives, itching 
• Blistering, shedding, or peeling skin
• Flu-like symptoms
• Tingling, pins and needles, numbness
• Pain or swelling of the sinuses
• Ear pain or fever in children

Singulair has been reported to cause new or worsening mental health problems. Stop taking Singulair and talk to your doctor immediately if you experience any unusual changes in mood or behavior, including:

• Anxiety, depression, confusion
• Aggression, agitation
• Hallucinations, vivid dreams
• Suicidal thoughts, ideations, or actions

The above list may not include all the potential side effects of Singulair. Speak to your doctor if you have severe side effects or if the side effects do not get better. You can also report unusual Singulair side effects to the Food and Drug Administration at 1-800-FDA-1088.

Singulair Overdose: In case of a known or suspected Singulair overdose, call the poison control helpline at 1-800-222-1222 or call 911. Symptoms of Singulair overdose may include stomachache, headache, sleepiness, thirst, vomiting, or agitation. Speak to your doctor or pharmacist as soon as possible if you’ve taken extra doses of Singulair, even if you don’t have any of the above symptoms. 

NOTE: Singulair is a prescription medicine intended to be used only by you—never share your Singulair with others or use someone else’s Singulair.

Source: FDA