1 00:00:02,040 --> 00:00:07,480 Speaker 1: Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff, 2 00:00:07,520 --> 00:00:11,240 Speaker 1: Lauren bug Bomb here. When Alexandra Allen was twelve years old, 3 00:00:11,320 --> 00:00:12,960 Speaker 1: she did what most kids do when they're on a 4 00:00:13,000 --> 00:00:15,880 Speaker 1: family vacation. She went for a swim in the hotel pool. 5 00:00:16,600 --> 00:00:20,119 Speaker 1: Unlike most kids, though, Alexandra had a severe reaction to 6 00:00:20,160 --> 00:00:23,200 Speaker 1: her swim. Her skin broke out and angry, itchy welts 7 00:00:23,280 --> 00:00:26,040 Speaker 1: just a few short hours after leaving the water. What 8 00:00:26,160 --> 00:00:28,760 Speaker 1: began as an ordinary summer day ended in the eventual 9 00:00:28,800 --> 00:00:32,360 Speaker 1: diagnosis that would change Allan's life. She shelved her dreams 10 00:00:32,360 --> 00:00:34,160 Speaker 1: of living on a sailboat and working as a marine 11 00:00:34,159 --> 00:00:38,479 Speaker 1: biologist after discovering she was allergic to water. An allergy 12 00:00:38,479 --> 00:00:42,120 Speaker 1: to water seems like an improbable condition. After all, water 13 00:00:42,240 --> 00:00:45,160 Speaker 1: is a chief chemical component in the human body, accounting 14 00:00:45,159 --> 00:00:48,240 Speaker 1: for at least six of the average person's weight. Water 15 00:00:48,280 --> 00:00:52,160 Speaker 1: whisks toxins out of critical organs, fairies nutrients to hungry cells, 16 00:00:52,360 --> 00:00:55,200 Speaker 1: and creates the human conditions needed for ear nose, and 17 00:00:55,280 --> 00:00:59,320 Speaker 1: throat health. In short, water is essential to life. In 18 00:00:59,360 --> 00:01:02,040 Speaker 1: the case of water are allergies, only the skin is affected. 19 00:01:02,360 --> 00:01:05,280 Speaker 1: People with this condition can still safely drink water. It's 20 00:01:05,280 --> 00:01:08,000 Speaker 1: only when water of any temperature or origin touches the 21 00:01:08,040 --> 00:01:12,720 Speaker 1: skin that a hypersensitive allergic reaction occurs. The condition, known 22 00:01:12,720 --> 00:01:16,760 Speaker 1: as aquagenic uticaria, is called an allergy, but isn't medically 23 00:01:16,760 --> 00:01:20,319 Speaker 1: classified as a true allergy. It's actually an allergy like 24 00:01:20,520 --> 00:01:23,920 Speaker 1: reaction that belongs to a subset of physical r tucaria, 25 00:01:24,240 --> 00:01:27,080 Speaker 1: a group of conditions characterized by hives or welts that 26 00:01:27,120 --> 00:01:30,080 Speaker 1: arise from stimulation of the skin. In the case of 27 00:01:30,080 --> 00:01:34,119 Speaker 1: aquagenic ur tcaria, red swollen, itchy bumps form when water 28 00:01:34,200 --> 00:01:37,640 Speaker 1: touches the skin. This histamine reaction isn't directed at the 29 00:01:37,680 --> 00:01:40,600 Speaker 1: water itself, but is most likely a reaction to a 30 00:01:40,600 --> 00:01:45,679 Speaker 1: water soluble antigen that stimulates antibodies. Any type of water, distilled, 31 00:01:45,720 --> 00:01:49,000 Speaker 1: tap or rain will cause an outbreak almost immediately, and 32 00:01:49,160 --> 00:01:51,840 Speaker 1: can make bathing or getting caught outside in a rainstorm 33 00:01:51,880 --> 00:01:56,720 Speaker 1: a tortuous proposition. Aquagenic Uricaria is so rare that fewer 34 00:01:56,760 --> 00:01:59,960 Speaker 1: than one occurrences have been recorded in medical literature since 35 00:02:00,040 --> 00:02:03,160 Speaker 1: the first cases were described in nineteen sixty four. It 36 00:02:03,200 --> 00:02:06,200 Speaker 1: affects women more than men, and most often begins during puberty. 37 00:02:06,600 --> 00:02:09,880 Speaker 1: It's usually diagnosed by putting the skin into prolonged contact 38 00:02:09,960 --> 00:02:12,880 Speaker 1: with water. In Alan's case, physicians asked her to soak 39 00:02:12,880 --> 00:02:16,160 Speaker 1: in a tub to diagnose the condition. The cause of 40 00:02:16,200 --> 00:02:19,960 Speaker 1: these water allergies still eludes experts. One theory is that 41 00:02:20,040 --> 00:02:23,000 Speaker 1: sweat glands could be the culprit. It's possible that sweat 42 00:02:23,040 --> 00:02:25,440 Speaker 1: glands in certain people produce a toxin that leads to 43 00:02:25,480 --> 00:02:29,240 Speaker 1: an allergic reaction with water. While researchers remain on shore 44 00:02:29,240 --> 00:02:31,680 Speaker 1: of the root cause of the condition. Most cases can 45 00:02:31,720 --> 00:02:34,800 Speaker 1: be treated with antihistamines and controlled by avoiding contact with 46 00:02:34,840 --> 00:02:42,680 Speaker 1: water as much as possible. Today's episode was written by 47 00:02:42,760 --> 00:02:45,680 Speaker 1: Laurie L. Dove and produced by Tristan McNeil. For more 48 00:02:45,680 --> 00:02:47,920 Speaker 1: on this and lots of other weird topics, visit our 49 00:02:47,960 --> 00:03:01,560 Speaker 1: home planet, how Stuff Works dot com.