Just what are we allergic to? Nuts, insect stings, and penicillin may be among the most familiar allergy-causing substances out there, but they're just the tip of a very big iceberg.
Here are 12 often-overlooked things that cause allergic (or allergy-like) reactions, from Dr. Andrew Nish, an allergist in private practice in Gainesville, Georgia and an AAAAI fellow.
The Wicked Witch of the West was all wet, but no one really melts when they're drenched with water.
Still, water can give some people hives - especially when it contains chemicals, says Dr. Nish.
Doctors call this rare sensitivity aquagenic (caused by water) urticaria (hives). But whatever you call it, antihistamines can help.
Vampires they're not, but some people break out in hives when exposed to sunlight. Seems the problem is sensitivity to particular wavelengths of light. The primary treatment for solar urticaria is simple: avoiding the sun. Medicines can help too.
For some, a kiss can leave them hot and bothered - and not in a good way. We're talking about smooches that deliver small amounts of irritating foods or chemicals. Symptoms can include itching and swelling of the mouth and face.
Can people really be allergic to sex? Not really. But some women are allergic to their partner's seminal fluid. It can leave the vagina red, swollen, and itchy - and in severe cases can lead to the severe allergic reaction known as anaphylaxis.
For a woman with seminal fluid allergy, condoms can help. Of course, some women are allergic to latex condoms.
The allergy affects less than 1percent of the U.S. population, according to the American Academy of Allergy, Asthma & Immunology.
Bad news for some beer connoisseurs: Hops and barley can cause an allergic reaction marked by a rash, shortness of breath, or stomach upset. If you're affected, your best bet is to find a new drink.
Are some people really allergic to cold? Not really. But for some, low temperatures cause the skin to release histamine, resulting in hives.
It can be a potentially dangerous condition. For some people with cold urticaria, a plunge into cold water could trigger a deadly reaction, says Dr. Nish.
Don't worry, listening to heavy metal won't give you a rash. But exposure to the metal found in portable music players, cell phones, belt buckles and jewelry causes some people to break out. It's not a true allergy, says Dr. Nish, but a form of a skin condition known as contact dermatitis.
While kids might want to claim they're allergic to a math test or college interview, a "pressure allergy" is something else entirely. It's a hive-producing condition caused by tight belts, bras, or underwear. Got a pressure rash? An antihistamine might help.
It's a bittersweet truth: cacao, the main ingredient in chocolate, can cause allergic reactions that cause breathing trouble, rash, and stomach upset. Avoiding chocolate solves the problem, of course, but some doctors prescribe an adrenaline injector just in case of accidental ingestion.
Lots of us say we are allergic to exercise, but for a small group of people it's almost true.
Some people develop a condition known as cholinergic urticaria when they get too hot and sweaty - typically when they work out very hard.
Antihistamines can help.
Here's an excuse for not mowing the lawn: Vibrations from lawn mowers, jackhammers, and the like can cause hives or swelling, according to Dr. Nish.
Hard to believe, but some medications used to treat allergies can actually cause them. Steroids, antihistamines, and even adrenaline can cause symptoms. Typically, the problem lies with additives in the medications. Of course, some people are allergic to drugs used to treat other conditions, such as antibiotics like penicillin.