Hello Asthalin syrup i.e. salbutamol ,ambroxole, guaiphenesin+menthol . Asthalin expectoration i.e. salbutamol + guaiphenesin . The doses of salbutamol and guaiphenesin is just double in expectoration than syrup . While syrup also contains mucus reliever . While alerid is ceterizine . As these both syrup acts as anti histamine and provide relief in cold and act as anti allergen. Allergy may be the main cause of cold in your baby so your doctor prescribed right drugs . As far as side effects ,these are minimum as nausea, mild sedation ( help in 10 months baby) , mild palpitation and fine tremors ( but side effects are not serious at all ). So you can use these medicine , even for prolong time and use whenever require . Good luck.