immediate allergy vs allergy

immediate allergy and allergy both are nouns.

Word	Noun	Adjective	Verb	Adverb
immediate allergy	Yes	No	No	No
allergy	Yes	No	No	No

As nouns, allergy is a hypernym of immediate allergy; that is, allergy is a word with a broader meaning than immediate allergy:

immediate allergy: an allergic reaction that becomes apparent in a sensitized person only minutes after contact
allergy: hypersensitivity reaction to a particular allergen; symptoms can vary greatly in intensity

Other hypernyms of immediate allergy include allergic reaction.

immediate allergy (noun)	allergy (noun)
an allergic reaction that becomes apparent in a sensitized person only minutes after contact	hypersensitivity reaction to a particular allergen; symptoms can vary greatly in intensity