This is a very difficult question to answer. Ceftin is a cephalosporin-type antibiotic which has a similar chemical structure to penicillin. Patients with severe reactions to penicillin (anaphylaxis,...
Cefpodoxime is a cephalosporin type antibiotic, not a penicillin itself. Though there is a slight possibility of cross-reactivity, in actual practice the cephalosporin cans still be safely given...
Flexeril brand of cyclobenzeprine is a muscle relaxant.
Penicillin is an antibiotic.
Those drugs generally do not interact with each other, so allergies to one will usually not cause any problems...