Hello. Apetamin is a vitamin syrup said to benefit weight gain. Hypothyroidism is an endocrine condition which by itself will cause weight gain along with other symptoms like cold intolerance, hoarseness of voice, etc. Treatment of hypothyroidism is essential and needs to be continued. Also, there is no harm in taking both the thyroid supplements and Apetamin together - provided that there is a gap of atleast an hour between the two. However, if you are looking to gain weight, you need to keep checking your thyroid profile regularly as over treatment causes weight loss. Hope this helps. Regards, Dr Geeta