When i was an infant, i had an allergic reaction to erythromycin. i still tell docs that i'm allergic to that med. is this still necessary?

PROBABLY, but...: Your 'allergy' to an antibiotic as an infant may not have been a true allergy e.g. What was the reaction? Rash? Or other reaction? The 'allergy' may or may not still exist in you currently but we usually do not take any chances. We hardly use Erythromycin anymore so it is easy to get around.

Depends: Many of the kids reacting to Erythromycin years ago simply had a gut that didn't like it.If thr reaction was simple vomiting & belly pain it was more likely intolerance & not a true allergy.Either way, you should always share medication reactions with your doc. If s/he decides you need something from that medication family it will make it easier to chose wisely.