Is it possible to consume alcohol when you are prescribed a steroid, ic methylprednisolone for a skin rash? What are the side affects of consuming alcohol while you are on this steroid? What would happen if you do consume alcohol while on this steroid?

Nothing. I always wonder what someone means when they say 'consuming alcohol.' if we are talking one or two social drinks a few times a week, then the answer is nothing. If we are talking about getting drunk every day, every other day, then it is not good for you or your skin. There are no specific interactions between beverage alcohol and steroids used on the skin.
Even . Even though there is no "official" interaction between Methylprednisolone (a steroid) and alcohol, we generally recommend avoiding the combo because they can exacerbate each other's side effects. For example: both steroids and alcohol can cause gastritis and stomach upset, so the two together can make this side effect even more likely and more severe. Another reason why we generally advise avoiding alcohol with steroids is because some of the illnesses we use steroids to treat (like ulcerative colitis) can be made worse with alcohol consumption. This may not pertain to you with your rash, though. If you are still not sure, give your doctor a call.