In 1910 British scientists discovered a chemical called histamine that was released during an allergic reaction, and they determined it was this substance that was responsible for causing tissues to become inflamed. A year later Henry Dale proved that injecting histamine into guinea pigs and dogs would instigate the allergic response.
This discovery gave scientists a lot of hope. Originally they beleived histamine was the only cause of allergies and that finding a treatment for histamine would mean allergies would be eliminated. Yet later scientists learned this was not true, that allergies were a series of complex reactions.
In 2007 Gregg A. Minton explains how "in 1921 Carl Pransnitz attempted to further understand allergies by injecting into his abdomen the serum from his colleague Heinz Kustner, who had a severe allergy to fish. Prausnitz had no such allergy, but when he sat down to a fish dinner, he found that a case of the hives appeared on his body at the injection site. The experiment demonstrated that a specific immune body -- later known as an antibody -- was present in the serum of allergic patients. The substance could be passively transferred to nonallergic individuals, and it played a crucial role in the allergic reaction." (1, page 215)
This experiment lead researchers to think that if they could figure out what this "antibody" was they could unlock the mystery of allergies and eliminate this annoying malady from existence. (1, page 215) So the hunt was on.
In the meantime, Daniel Bovet introduced a medicine that blocked the effects of histamine in 1937, and he called this new medicine an antihistamine. It was the first truly effective medicine to treat the symptoms of allergies. By blocking the effects of histamine it therefore prevented an allergen from causing a stuffy and runny nose, itchy eyes, nose and throat, and sneezing.
The next discovery was Benadryl. Minton explains it was discovered by 21 year old professor at Cincinnati University named George Rieveschi. He was trying to create an antispasmotic drug when he inadvertently discovered the "new compound in his laboratory." (1, page 216)
In 1946 the first two antihistamines hit the market: Benadryl and Pryibenzamine. Minton describes how "antihistamines became, next to antibiotics and barbituates, the third most commonly prescribed class of drugs in America." (1, page 213)
Minton explains that other antihistamines hit the market in 1947, but Benadryl and Prybenzamine made up the bulk of the sales. In 1947 Hydrillin hit the market, which was a product that had both an antihistamine and a bronchodilator called theophylline. This relieved allergy symptoms and made breathing easier, an ideal remedy for people suffering from allergic asthma (which, as it turns out, includes about 75 percent of all asthmatics)
Theophylline is a medicine that was first introduced to the world in 1930 as another antispasmotic medicine for asthma. It was a medicine that relaxed the smooth muscles that lined the air passages of the lungs and made breathing easier. This new medicine provided another over the counter option for allergy and asthma sufferers. (I wrote about theophylline here.)
In 1949 Neohetramine was the first antihistamine approved by the Food and Drug Administration (FDA) as an over the counter medicine. Other antihistamines soon followed. Minton notes that "by 1950, more than 21 antihistamine compounds packaged under one hundred different trade names in tablets, nasal sprays, eye drops, and creams on the market in the United States." (1, page 216-217)
- Mittman, Gregg, "Breathing Space," 2007, New Haven and London, Yale University Press