Montair Plus is a Fixed-Dose Combination of two medicines: montelukast and bambuterol. Therefore their side effects get added up.
Montelukast side effects include: abdominal pain, headache, and thirst. Sometimes severe allergy, angiooedema, seizure, elevated liver tests, cholestatic hepatitis, Churg-Strauss syndrome etc. Some of these side effects may appear immediately whole others after prolonged therapy.
Bambuterols side effects include: Lowering of potassium levels in blood, tremors, headache, cramps, palpitations, urticaria, exanthema, heart movement abnormalities and sleep disturbance. Some of these side effects may appear immediately whole others after prolonged therapy.
It is not necessary that all side effects would appear in all patients.
Fixed-Dose Combinations (FDCs): Medicines are discovered individually and are supposed to be taken separately. A huge number of irrational, illegal combinations of drugs are being sold in India; quite a few without mandatory approval of the Drugs Controller General, India (DCGI). Except in a few cases (such as TB medicines), it is always better to take medicines separately so that dosage can be adjusted and side effects monitored.