How would i go about confirming a caffeine allergy/ intolerance? when i consume caffeine i have what seems to be an anaphylactic reaction.

Not likely: Caffeine is a small molecule that rarely, if ever, causes anaphylaxis. Like any other possible allergen a skin test is performed. If history is convincing & test positive no further testing is required. Otherwise a blinded challenge is done in the office.

Distinctly Unusual: Caffeine allergy is unusual but has been reported in the literature. After speaking to your allergist and clarifying your history, there are several options that could be explored. Skin testing could be done but there is no standardized skin test reagents for caffeine thus the results must be interpreted with care. Oral challenges could be considered but only with your physicians supervision.