SINGULAIR 4 mg Tablets: pink, oval, bi-convex-shaped chewable tablets, with code MSD 711 on one side and SINGULAIR on the other. NDC 0006-1711-31 unit of use high-density polyethylene (HDPE) bottles of 30 with a polypropylene child- resistant cap, an aluminum foil induction seal, and silica gel desiccant. Singulair side effects. Get emergency medical help if you have signs of an allergic reaction to Singulair: hives, blisters, severe itching; difficult breathing; swelling of your face, lips, tongue, or throat. Tell your doctor right away if you have signs of blood vessel inflammation: flu-like symptoms, severe sinus pain, a skin rash, numbness or a pins and needles feeling in your arms or. For both adults and children, side effects with Singulair are generally mild and not very common. The more common side effects of Singulair involve the respiratory system and can include the common cold, fever, and headaches. The FDA also recently published an announcement emphasizing that montelukast can cause mental health side effects, including suicidal thoughts and actions. Find everything you need to know about Singulair (Montelukast), including what it is used for, warnings, reviews, side effects, and interactions. Learn more about Singulair (Montelukast) at. FDA requires a Boxed Warning about serious mental health side effects for the asthma & allergy drug Singulair (montelukast). Only take montelukast for hay fever if other medicines do not work or. Montelukast (Singulair) is a drug prescribed for the treatment of asthma and hay fever (seasonal allergic rhinitis). Side effects, drug interactions, warnings and precautions, and patient information should be reviewed prior to taking any medication. Side effects of Singulair include: skin rash, mood changes, tremors, headache, stomach pain, heartburn, upset stomach, nausea, diarrhea, tooth pain, tiredness, fever, stuffy nose, sore throat, cough, and hoarseness. Dosage for Singulair. The following doses of Singulair are recommended: For adults and adolescents 15 years of age and older: one 10-mg tablet. For pediatric patients 6 to 14 years. Side effects requiring immediate medical attention. Along with its needed effects, montelukast (the active ingredient contained in Singulair) may cause some unwanted effects.Although not all of these side effects may occur, if they do occur they may need medical attention. However, Singulair has severe side effects related to mood, which have caused controversy in recent years. The drug can also provide relief for seasonal, indoor, and outdoor allergies. Find patient medical information for Singulair oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings.