Hello dear,
Most of the weight gain supplements are prepared from herbal ingredients & do not have any side effects if taken in the optimum dose.
But, before choosing any such health supplement, it is advisable to consult your family physician once.
Also make sure they do not contain
steroids...as intake of such a supplement will cause harm in the long run.
Moreover, you should not compromise on routine healthy food such as:
1. Consume more of natural diet like fresh fruits, green vegetables, milk, eggs, wheat, etc.
2. Avoid oily and junk food.
3. Stay away from smoking & alcohol.
Despite these measures, if you experience difficulty, it will be better to rule other causes of
underweight.
Investigations like
complete blood count,
thyroid profile, estimation of blood sugar level will be helpful.
Most importantly, do not make hurry in building up muscles.
The
metabolism of the body functions at its normal rate & any measures taken to hasten up this process can be harmful.
Wishing you a healthy life.
Take care.