For most healthy adults, one daily Celsius drink is unlikely harmful. However, these drinks are high in caffeine (200–270 mg per can). The FDA states that 400 milligrams or less of caffeine per day is typically not associated with adverse health impacts. However, individual tolerance to caffeine can vary; check with your healthcare provider if you are unsure.For most healthy adults, one daily Celsius drink is unlikely harmful. However, these drinks are high in caffeine (200–270 mg per can). The FDA states that 400 milligrams or less of caffeine per day is typically not associated with adverse health impacts. However, individual tolerance to caffeine can vary; check with your healthcare provider if you are unsure.