Can u get a rash with mono?

Yes: Early symptoms are severe fatigue, headache, sore throat, chills, followed by fever and muscle aches. After day or two, swollen nodes, jaundice, measles like rash, and sore left upper abdomen secondary to enlarged spleen, and red spots on roof of mouth.

Rash: If you use a penicillin antibiotic. I do not remember the mechanism but is is an interaction between the virus and the antibiotic anyway it is self limited and does not mean you have an allergy to penicillin. Good luck!