Allergy
An allergy or allergic reaction referred to a body's inappropriate immune response to various stimuli, usually proteins. These stimuli were called allergens. ()

The body's responses could be minimal such as snoring, but could also include anaphylactic shock or even death. Allergies often had a genetic basis. They could be present from birth or could present themselves at any later point during a lifetime.

In the 23rd century, in the medical history section of Christopher Pikes personnel file, an allergic reaction was listed with other ailments he had suffered during his lifetime prior to 2257. ()

In 2258 of the alternate reality,  suffered an allergic reaction to the antidote for a virus carried by Melvaran mud fleas administered by Doctor . ()

In 2369, Odo told Quark that "the something" in Jadzia Dax's eye was an allergic reaction to him. ()

Later that year Julian Bashir thought he had taken an allergic reaction to replicated antipasto and was hallucinating an affectionate Jadzia Dax. ()

When Elim Garak made Odo a Bajoran Militia uniform in late 2372, he asked him if he was allergic to Inkarian wool. ()

Species allergies 
 The inhabitants to Sirius IX were allergic to a love potion sold to them by Harry Mudd. ()
 Humans were allergic to Ferengi blood pyrocytes. ()
 Joined Trill were extremely allergic to insect bites. The reaction caused by the insect's venom interfered with the biochemical connections between the host and symbiont. ()

Individual allergies 
 Henry Janeway was allergic to chocolate, preferring oatmeal cookies instead. ()
 Travis Mayweather was allergic to a pain medicine he was once given on Risa. ()
 Malcolm Reed was allergic to bromelain, for which he took regular injections. He was also allergic to dust mites, oak pollen, and tropical grasses. () 
 Sylvia Tilly was allergic to polyester and viscoelastic polyurethane foam. ()
 James T. Kirk was allergic to Retinax V, an eye medication. ()
 was allergic to the vaccine for the Melvaran mud flea virus. ()
 Wesley Crusher was allergic to metorapan, an analgesic medication. He was treated with bicaridine instead. ()
 Quark once stated he was "allergic to nature." ()
 Commander Zakarian was allergic to many things earning him the nickname "Old Sneezy". ()
 Jadzia Dax was allergic to icoberry juice – it made her spots itch – but she drank it anyway because she liked the taste. () 
 While undergoing hyper-evolution, Tom Paris had an allergic reaction to the water Neelix used for the coffee "Paris Delight". ()
 Neelix, while he had ingested leola root in many forms, discovered his skin was allergic to leola ointment, a topical Talaxian homeopathy remedy for sunburn.  It caused discoloration, swelling and blistering to the applied areas. ()

See also 
 Histamine

External link 
 

de:Allergie
Medical conditions