type I allergic reaction vs atopy

type I allergic reaction and atopy both are nouns.

Word	Noun	Adjective	Verb	Adverb
type I allergic reaction	Yes	No	No	No
atopy	Yes	No	No	No

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

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

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

type I allergic reaction (noun)	atopy (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