Keflex is not a sulfa med., and although I'm allergic to PCN, I'm able to take Keflex and several other Cephalosporins (Cipro for example) with no problems. I'm also allergic to Tequin, but can take Levaquin with no problems, either. Go figure?
Ds10 did well on Keflex for an infected bug bite. No side effects at all.