Types of Side Effects

In adults, side effects with Singulair include weakness, fevers, indigestion, dental pain, dizziness, headaches, nasal congestion, coughing and skin rashes. The most common side effects in children are pharyngitis, fevers, sinus infections, nausea, diarrhea, indigestion and ear infections.

Drug Interactions

Prescription medications like the barbiturate phenobarbital or the antibiotic rifampin pose an increased risk for side effects when taken with Singulair, reports the U.S. National Library of Medicine.

Risks

Although rare, Singulair causes neurological and psychiatric side effects in some patients. These may include hostility, anxiousness, depression and suicidal thoughts, hallucinations, insomnia, irritability, restlessness, sleep walking and shaking, warns the U.S. National Library of Medicine. Other risks include severe allergic reactions, pancreatic inflammation, liver dysfunction and vasculitis or inflammation of your blood vessels.

Warning

Suddenly discontinuing use of Singulair may cause a severe asthma attack, warns the Mayo Clinic. Because of this, you should not stop taking the drug without first consulting your doctor, even if you experience side effects.

Considerations

Because the drug is known to cause fetal harm in laboratory animals, doctors restrict use of Singulair in pregnant women to instances where there is no safe alternative to treatment. If you have a history of an allergy to aspirin or non-steroidal anti-inflammatory medications, liver disease or phenylketonuria, it may not be safe for you to take Singulair, cautions the Mayo Clinic.

Source:

U.S. National Library of Medicine: singulair (montelukast sodium) granule

Mayo Clinic: Montelukast (Oral Route)