Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Servicio Nacional de Salud del Reino Unido Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? National Health Service de Gran Bretaña. Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach? Why must some medicines be taken on an empty stomach?