April showers bring May flowers—and seasonal allergies. For people who suffer from hay fever and other sensitivities—between 10 and 30 percent of the world’s population—pollen season can be an ordeal. But they can take some comfort in reflecting on the astounding progress that’s been made in treating these common—and potentially dangerous—maladies.
Allergies were known in ancient times, of course, and everyone from the Egyptians to the Romans had folk remedies for them. But only in the 19th century was pollen identified as the cause of hay fever. Also known as “allergic rhinitis” (from “rhinos,” Greek for “nose”), this condition is an inflammation of the nasal passages that, along with other symptoms, results when the immune system misidentifies pollen as a pathogen. In the 1900s, an Austrian pediatrician named Clemens von Pirquet coined the word “allergy” to describe the way patients often reacted severely to the second dose of a vaccine. Somehow the first dose, he realized, was priming their bodies to respond to the second.
The causal mechanism of allergies wasn’t understood until the 1950s, when scientists discovered that so-called mast cells work with white blood cells to fight what the body thinks are infections. When an allergen enters the bloodstream, a type of white blood cell called a B-lymphocyte produces a protein, immunoglobulin E, or “IgE,” tailored to that specific allergen. Like a targeting beacon, the IgE then signals mast cells to release chemicals that ordinarily help fight disease. The best known of these chemicals is histamine, which causes the itching and sneezing associated with seasonal allergies.
The first, and still most common anti-allergy medicines were designed to treat this unnecessary histamine release. Antihistamines such as diphenhydramine hydrochloride (Benadryl)—first sold in the United States in 1946—dampen histamine’s effects and relieve symptoms but have a well-known downside: They can cause drowsiness.
In the 1980s, scientists at a Belgian pharmaceutical company called UCB fashioned a new molecule, cetirizine, which provided many sufferers with greater relief. Sold today as Zyrtec, cetirizine is often called a “second-generation” antihistamine because unlike the shotgun approach that older antihistimes take, cetirizine and other second-generation drugs are designed at the molecular level to attach themselves to the spot on mast cells—known as the H1 receptor—that would normally receive signals sent by B-lymphocytes. Blocking the signal prevents the mast cell from releasing histamine.
Their greater precision means that second-generation antihistamines don’t cause drowsiness. H1 receptors are found not only on mast cells, but throughout the body, including the central nervous system—and muffling these receptors throughout the nervous system, as Benadryl does, makes people sleepy. Second-generation antihistamines, by contrast, affect only the receptors on mast cells, thus preventing histamine production without causing the annoying side effect.
Antihistamines aren’t the only allergy medicines, of course, and they don’t treat all allergies; much about allergies is still not understood. But they represent an astounding step forward in the quality of life of people who suffer from hay fever. And that raises an important point: Although the media tend to highlight research that fights deadly diseases such as cancer, the medicines that treat chronic maladies are also an essential part of the scientific progress that we too often take for granted—progress that focuses on improving, as well as lengthening, lives. Consider how many days people of previous generations lost to allergies—perhaps mistaken for diseases—or the many joyful experiences our great-grandparents missed out on, or enjoyed less than they could have, as a result of allergies.
Medicines that treat nonfatal or non-crippling maladies are sometimes regarded as trivial—or worse. Some bioethicists have expressed foreboding over what they consider the dehumanizing effects of remedies for mere discomforts. Leon Kass—chairman of President George W. Bush’s Council on Bioethics—has written that biological “limits” are “necessary for all the great human things” and that treatments that remove those limits—such as life-enhancing medicines—will reduce mankind to a “humanly debased condition.”1 Even many patients themselves feel there’s something vain or artificial about taking a pill for a discomfort they could just power through. But these concerns are factually and morally unfounded. Seemingly minor conditions such as allergic rhinitis can cause serious complications—and significant secondary consequences, as when people give themselves colds or the flu by rubbing their itchy eyes with unwashed hands. And even if it were true that suffering has spiritual “value”—as some, echoing an irrational, pre-Enlightenment belief, claim—the decision of whether to endure it should be made by the individual, not by bystanders who withhold medicine on the theory that “limits” are “necessary” for others.
One thing is clear: Although scientists still have a long way to go to cure all allergies, their hard work has given us more options than ever before to deal with springtime suffering—and improved our standard of living in incalculable ways.
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1. Leon Kass, “Preventing a Brave New World,” The New Republic Online, June 21, 2001, https://web.stanford.edu/~mvr2j/sfsu09/extra/Kass3.pdf (accessed May 20, 2019).