I dont like taking anything while pregnant but sometimes i cant keep my food down and im very nauseous 18 weeks doc gave me promethazine is it safe?

Yes: While Promethazine is a category c drug for pregnancy, the main concern is in the first trimester, which you have passed. You need to be able to have some degree of nutrition to properly take care of yourself and baby. Take the medication as prescribed, and contact your doctor if symptoms do not improve or if your have increasing concern.