The common side effects of Singulair include headache, heartburn, tiredness, ear infection and diarrhea, according to Everyday Health. Serious side effects include weak muscles, extreme sinus pain, skin rash and deteriorating asthma symptoms. Asthmatics should seek immediate medical care if they experience these serious side effects.
Singulair is name-brand montelukast, which is a medication for asthmatic patients, explains Everyday Health. When used by an asthmatic patient, this medication blocks leukotrienes, which are substances that inflame the lungs and constrict the air vessels in the body. It also reduces the rate at which asthma attacks an individual and can help curb asthma that results from exercise.
To take Singulair, the patient should follow the doctor's instructions strictly, says Drugs.com. This helps avoid overdose and keeps asthma symptoms under control. Typically, a patient should take Singulair once per day to help treat asthma. To prevent constriction of air passages caused by exercise, a patient should take one dose at least two hours prior to exercise and refrain from taking another dose for 24 hours. In case of a missed dose, the patient should take the missed dose as soon as possible and contact a doctor immediately in the event of an overdose.