GST Applicability on Drug Rehabilitation center

Yes if your services being provided under SAC CODE - 999341

This service code includes:
Vocational rehabilitation services for persons with disabilities, where the social assistance component is predominant.

Services supplied by rehabilitation professionals recognised under Rehabilitation Council of India Act, 1992 at medical establishments, educational institutions, rehabilitation centers established by Central Government / State Government or Union Territories or entity registered under section 12AA of the Income-tax Act shall be exempted.