I never get acne, but I have been on cephalexin for a week and my entire face and now starting down my neck is broke out. Can cephalexin cause acne?

Acne like drug reax. I do not think it is true acne, but may be an acneaform drug reaction. Some medications can cause an acne like eruption, and the treatment is to stop the medication. I would ask the doctor that gave you the antibiotic to see if it could switched to something else. If it does not improve in 3-4 weeks, i would see a dermatologist. I hope this helps. Lana long, M.D.