Can I take cloxacillin if I'm allergic to penicillin?? ## Hi Gavin, From what I've read, the answer to your question is actually no. Reason being is that Cloxacillin is a semisynthetic antibiotic in the same class as Penicillin. The manufacturer's guidelines also recommend that no one should take this drug with an allergy to cloxacillin, any penicillin, or any other part of this medication. You can learn more about this drug on the page for Cloxacillin Details I hope this info helps! ## Hi I was just clarifying this as even though on my admission forms and actually stating to the doctor at Sunninghill hospital I was still prescribed cloxacillin!!!!!!! I need to take this matter further with the hospital as they could have killed me!!!! Thanks for reply