My dad wants to gain weight but he can't he's tried a medicine called megace (megestrol) and it hasn't worked yet. he just wants to gain 10 pounds.

Weight gain: More information is needed. Does your dad have any illness that could be causing weight loss? Hopefully his doctor prescribed the megace (megestrol). It may take a while for this medicine to increase the appetite. He needs to discuss the dose of med with his doctor. It may need to be adjusted. Also he may need some food supplements to increase the calorie intake. These should be discussed with the doctor.