Si vas al médico y te receta una medicina, das por sentado que no implica riesgos.If you go to a doctor and he prescribes you a medicine, you take it for granted that it's safe.
¿Qué te dice tu médica cuando te receta una medicina? - Come algo antes de tomarla.What does your doctor tell you when she prescribes you a medicine? - Eat something before you take it.