My dog licks my skin. Can my human meds harm her if she licks me?

Sassy sounds like a sweetheart and a wonderful companion! Any oral/intravenous medications you are taking for MS are unlikely to pose as a risk to Sassy from her licking your skin. However many treatments for MS such as steroids can cause immunosuppression and put you at greater risk for zoonotic diseases that can be transmitted from dogs to humans such as intestinal parasites (roundworms, hookworms, whipworms), leptospirosis which can be transmitted through the urine of rodents and wildlife, tapeworms which can be transmitted by fleas. For these reasons it is recommended to keep her on monthly heartworm/roundworm prevention such as Heartgard, monthly flea/tick prevention such as Simparica, have her up to date on all vaccines including lepto, and to bring her into the veterinarian quickly if she ever has diarrhea as giardia is a zoonotic disease (transmissible to humans) that can cause diarrhea. Establishing a good rapport with your veterinarian with regular (every 6 months) check ups would be beneficial for your health as well as hers. She is adorable! Best wishes!