Hello dear, It is not advisable to take any medication for weight gain, because: 1. The medications interfere with the normal metabolic rate of the body & causes a number of side effects 2. The individual tends to lose more weight after stoppage of the medication. Before choosing any such medication or health supplement, it is advisable to consult your family physician once. They may be harmful if taken for a prolonged time, such as: 1. They contain small amounts of steroids, and can lead to a number of bone-related problems. 2. High amount of protein can affect kidney & liver function. 3. High sugar levels can result in diabetes with long term use. 4. Hormonal imbalances, reduced sexual desire, depression, etc. 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 to rule out any chronic infection, hormonal and metabolic causes. Wishing you a healthy life. Take care.