Hi, expectorants are unlikely to be of any help to a 21-mth old child, they are only likely to make the cough
worse. Also, teething
has got nothing to do with condition of your child. It would be better if you nebulise her with a salbutamol+Normal saline solution 2-3 times a day for 4-5 days. You can also give her a broncho-dilator syrup along with that. Good luck.