If one of my rats is sick, is it okay to medicate her cage mate?

One of my rats has mycoplasma pulmonis. I've put them in different cages now, but they were together for awhile while one was displaying symptoms and I didn't realize it. The vet said to medicate the other one, since it's probably lying dormant in her system. I feel uncomfortable doing this when she isn't displaying any symptoms. Have any rat owners ever done this?