If you turn bright red after a short time after taking a antibiotic does this mean your allergic? can you get tested for all antibiotics allergies. if they inject it and you have a bad reaction do they have rescue meds. thank you?

It depends on the antibiotic. Vancomycin has a known reaction called redman syndrome which is not a true allergy, but rather a reaponse to the Antibiotic. It typically goes away with benadryl or on its own and does not mean you are allergic to it. Talk to your prescribing Dr for them to examine the response to this med. True allergic reactions typically show red spots or hives.