I am currently taking 200 mg of Prometrium inserted vaginally. My doctor wants me to switch to progesterone suppositories and take the Prometrium orally. I don't understand what the difference is between taking the Prometrium vaginally and a suppository. She said if I have too many side effects with the oral Prometrium I can stop and just do the progesterone suppository. How is that any different than the prometrium vaginally? I have almost a full bottle of prometrium. I'd hate to waste it if it's no different than a suppository.