Had serum sickness from penicillin allergy 25 yrs ago. i was thinking of being tested to see if i still have it. could this go away after all these yrs. is it worth being tested?

It's not worth to try unless you really need to be treated with Penicillin. Take care.

Serum sickness is a hypersensitivity reaction typically attributed to the therapeutic administration of foreign serum protein, e.g., botulinum antitoxin derived from horse serum. Hypersensitivity reaction to penicillin does not lead to serum sickness. No rationale to get tested for.