Hi hope you are well. There are injections but they are harmful and cause lots of side effects. It would be better if you cover it nutritionally. Consult à dietitian for a diet plan or ping me for an appointment.

Body weight reflects your nutritional status. Becoming fat is not a good solution. You need to gain muscle weught. Get yourself involve in some kind of regular physical activity. Have proper balanced meal. I have been giving my clients weight gain diet plans which help them gain weight at the rate of 700 gms per month. Injections won't help in long run. Further more emphasis on lean body mass through exersice and diet. I suggest you to get a complete body composition analysis done so that I can analyse the root cause. I have this machine at my clinic. Feel free to contact for a healthy weight gain.