type I allergic reaction vs atopic allergy

type I allergic reaction and atopic allergy both are nouns.

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

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

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

Other synonyms of type I allergic reaction include atopy, immediate allergy.

type I allergic reaction (noun)	atopic allergy (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