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Folklore teems with legendary beings who have uncanny powers—but even weirder weaknesses. Many of these mythical creatures have human analogs who walk among us, complete with unusual Achilles’ heels: strange allergies.

Most of these are so rare it’s near-impossible to calculate the odds of having one, unlike with more common allergies—for example, the odds a boy younger than 18 will have non-respiratory allergies in a year are 1 in 8.78, the odds an adult will have hay fever in a year are 1 in 13.22, and the odds an adult is allergic to eggs are 1 in 500.

Here is Book of Odds’ list of unusual allergies and sensitivities, and the fabled icons who embody them.

Water

Icon: The Wicked Witch of the West

Reality: Whether you see her as L. Frank Baum’s cackling evildoer or Gregory Maguire’s misunderstood green lady, Oz’s occidental sorceress had a wicked sensitivity to plain old H2O. Perhaps she suffered from a bad case of aquagenous urticaria—breaking out in hives upon contact with water. The rare condition is thought to be caused by extreme sensitivity to water additives like chlorine, and reports vary on whether it responds to antihistamines. (If it does, it’s a true allergy, involving the immune system; if not, it’s technically not an allergy.) Besides antihistamines, capsaicin cream and ultraviolet B are among the treatments that have been tried. By the way, the odds an adult believes in witches are 1 in 4.76.

Sunlight

Icon: Vampires

Reality: Sunlight irritated Count Dracula, killed Anne Rice’s charismatic creatures of the night, and exploded Buffy’s targets into dust. (Stephenie Meyer, apparently, hadn't read up on vampire lore before creating her own sun-resistant type for her Twilight series, freely admitting being “not at all informed about the horror genre.”) The odds an adult who plans to dress up for Halloween will be a vampire are 1 in 23.81. Real-life solar urticaria is less common, and sufferers don’t actually explode, nor do they glow; instead, they respond to direct sunlight with an itchy rash or hives. Like other allergies, a sun allergy is an inappropriate immune system response. It’s rare; most sun sensitivities derive from chemicals or medications in skin products like sunscreen or perfume. Similarly, cold urticaria is just what it sounds like—an allergic reaction to cold temperatures.

Sex

Icons: The Amazons

Reality: According to myth, no men were allowed in the territory of these legendary female warriors. To keep their tribe going, they visited a neighboring tribe once a year to mate (and then kept only the female children). No specific reason for their disdain for men has been recorded, so here’s a theory: they suffered from human seminal plasma hypersensitivity, where a woman is allergic to her male partner’s seminal fluid. The good news: part of the treatment, which involves gradual desensitization, requires the couple to have frequent sex. Apparently the Amazons never thought of that. Incidentally, the odds a woman has ever had revenge sex are 1 in 11.45.

Meat

Icon: Lisa Simpson

Reality: We're used to hearing about peanut allergies and lactose intolerance, but there's some evidence that meat allergies may be more common than once thought. A recent study found that alpha-gal, a carbohydrate found in meat, was the culprit in a significant number of previously unexplained cases of anaphylaxis. Anaphylactic shock is characterized by difficulty breathing and a steep drop in blood pressure; it can be fatal. While many people (and some cartoon characters) avoid meat for moral reasons—the odds an adult is a vegetarian are 1 in 31.36—an unlucky few have little choice.

Exercise

Icon: Jabba the Hut

Reality: Exercise-induced anaphylaxis may be related to foods or medications, but vigorous activity sets it off. Before giving up and becoming a couch potato, a sufferer can investigate which substance or situation, when combined with exercise, causes the reaction, which can include itching and redness, hives, swelling, and ultimately anaphylaxis. The odds an adult 35 - 44 will get the recommended amount of exercise in a week are 1 in 2.02.

Wood

Icon: Paul Bunyan

Reality: Bunyan, the giant mythical lumberjack, logged so enthusiastically one might think he had something against our woody friends. Maybe he had an allergy. Many types of wood, especially in the form of shavings and dust, have been reported to cause skin reactions and other problems. One unfortunate man in England discovered his allergy only after quitting his banking job to follow his dream of becoming a carpenter. Fortunately, he found a type of wood he wasn’t allergic to. Many types have been reported to induce allergic reactions. In the US, the odds an employed person 16 or older is a carpenter are 1 in 150.2.

Kryptonite

Icon: Superman

Reality: None. Kryptonite, like Superman, is imaginary, but krypton (small “k”) is a real chemical element: you can find it in the number 36 square on the periodic table. (The odds an employed person 16 or older is a chemist are 1 in 1,627.) As a noble gas, krypton is chemically unreactive, and thus unlikely to cause allergies in Earthlings, many of whom— 1 in 4.17—believe extraterrestrial beings have visited the Earth. And the odds an American adult reports having witnessed a UFO—perhaps containing a baby Superman?—are 1 in 5.81. Let’s just hope the spacecraft isn’t made of nickel. Nickel allergies are on the rise.