I have celiac disease, and also cannot gain weight, is apetamin safe to take, one doctor said it is not safe at all.

Ok but: This drug is same as Periactin- an antihistamine we used to use to stimulate appetite. HOwever it does cause most people to be drowsy and thus not the safest drug to choose. You likely have problem getting food without gluten and thus it is time for you to consult a dietitian. Make sure that you don't have another disease condition which may cause weight loss.