immediate allergy vs type I allergic reaction

immediate allergy and type I allergic reaction both are nouns.

Word	Noun	Adjective	Verb	Adverb
immediate allergy	Yes	No	No	No
type I allergic reaction	Yes	No	No	No

As nouns, immediate allergy and type I allergic reaction are synonyms defined as:

immediate allergy and type I allergic reaction: an allergic reaction that becomes apparent in a sensitized person only minutes after contact

Other synonyms of immediate allergy include atopic allergy, atopy.

immediate allergy (noun)	type I allergic reaction (noun)
an allergic reaction that becomes apparent in a sensitized person only minutes after contact	an allergic reaction that becomes apparent in a sensitized person only minutes after contact