Here’s What Happens to Your Body During Anaphylaxis

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According to the Centers for Disease Control and Prevention, allergies affect more than 50 million Americans every year—and anaphylaxis, the most severe allergic reaction, affects at least 1.6 percent of the general population [PDF]. Here’s the science of what happens to the body during anaphylactic shock.

ALLERGEN EXPOSURE

In a person with allergies, cells sometimes identify foreign but innocuous stimuli as major threats. Why some people are allergic to certain things while others are not is a mystery science hasn't yet solved, but we do know how it happens: through a process called sensitization.

Here’s how it works. When the body encounters a foreign substance, also called an antigen, immune system cells deliver some of substance's molecules to T-helper cells living in the lymph nodes. Those cells also bring along a type of molecule that informs a T-helper cell it’s time to stage an immune response. Known as a costimulatory molecule, it's necessary to activate any type of immune system reaction involving T cells, whether you have allergies or not.

Being exposed to an antigen "primes" a T-helper cell, turning it into a Th2 cell. Primed Th2 cells release proteins called interleukins, which do two things: First, they interact with another type of immune cell called B cells to produce infection-fighting antibodies that bind to mast cells, which contain chemical particles they'll release in the presence of an antigen. Second, the interleukins activate eosinophils, a type of white blood cell that discharges toxic substances to destroy invading cells (and, occasionally, host cells). In this process, the immune system identifies the "threat" and deploys cells prepared to fight it. The immune system's elevated level of awareness of and preparation against the antigen reclassifies the substance as an allergen—a considerably more dangerous threat.

Because an allergy only develops after this process, a person allergic to strawberries, for example, will only experience a reaction the next time they eat something containing strawberries. New allergies can pop up at any point in your life.

An immune system on allergies is a little bit like a brain that can't distinguish a piece of lint from a spider: unable to relax, constantly on guard against every potential threat. After initial exposure, the mast cells activated during the sensitization phase are still equipped with allergen-specific antibodies and remain combat-ready, prepared to respond immediately should a second exposure ever occur. If it does—and it probably will—here’s what you can expect to happen.

ALLERGIC REACTION

If two or more allergen molecules bind to a sensitized mast cell, the mast cell releases inflammatory mediators that produce an allergic reaction. These mediators include substances like histamine and more of the interleukins that, in turn, activate eosinophils, Th2 cells, and basophils (another type of white blood cell). In a non-allergic reaction, mediators produce helpful inflammation that prevents infection and initiates healing—but those same symptoms can be annoying and even dangerous when the immune system attacks an otherwise benign allergen. Mast cells also release leukotrienes, which recruit more immune cells to the area and speed up the reaction. That leads to what Stanford University researcher Tina Sindher calls a “‘chain reaction’ of allergic inflammation.”

With the release of histamine, you might experience both bronchial contraction—which makes it more difficult to breathe—and blood vessel dilation. The latter makes it easier for blood to flow to affected areas, but it also makes blood vessels more permeable, allowing blood to escape from the blood vessel walls and flow into the spaces between cells and causing swelling and hives.

For most, these symptoms are merely uncomfortable; they can occur as late as eight to 12 hours after initial exposure, long after the allergen is gone, and can be alleviated with an antihistamine like Benadryl. But for a person with severe allergies, a life-threatening allergic response can occur within minutes: Their airways will constrict so much they won't be able to breathe, and their blood vessels will be unable to contract, which can lead to a drop in a blood pressure and keep veins from getting blood back to the heart. The combination of airway constriction and blood vessel dilation can make it impossible for the body to supply enough oxygen to major organs—that's anaphylactic shock.

The only way to stop anaphylaxis in its tracks is with epinephrine, more commonly known as adrenaline. Adrenaline is a hormone naturally produced by the adrenal glands to help generate the "fight or flight" response in emergency situations. It works by constricting certain blood vessels, increasing blood pressure, and relaxing airways, counteracting all the reactions produced by histamines.

According to Sindher, it’s important to use epinephrine immediately if you're at risk for anaphylactic shock. “There’s a general belief out there that epinephrine should only be used in the worst-case scenario,” she tells Mental Floss. “In fact, most of the complications we see in food allergic reactions are due to delayed use in Epi. Antihistamines can be helpful in treating the symptoms of itching and congestion, but they do not help stop an allergic reaction.”

THE FUTURE OF ALLERGY TREATMENT

Researchers like Sindher are still trying to understand what causes allergies, and why the prevalence of food allergies has increased over the past few decades. Sindher’s main goal is to find new ways of treating (and hopefully curing) allergies. The most established technique (for food allergies, at least) is oral immunotherapy, where allergic individuals gradually eat more of their allergen until they can have small amounts without experiencing a reaction. That’s usually done extremely gradually, over the course of months or years, and always under the supervision of a certified allergist.

image of two epipens sitting on a desk
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Sindher says scientists are still testing other types of immunotherapy treatments and vaccinations in clinical trials: “A lot of research is going into trying to identify the causes so we can be successful in the prevention as well as treatment of food allergies.”

Until that happens, though, doctors say the best course of action is to be careful around allergens. Medications are useful and necessary, but prevention is the name of the game when it comes to allergies.

The Ohio State Fair Is Hosting a ‘Sensory Day’ for Individuals With Autism

Halfpoint/iStock via Getty Images
Halfpoint/iStock via Getty Images

The Ohio State Fair has been a local tradition since 1850, and this year, fair organizers are trying something different. On Wednesday, July 31, 2019, the Columbus, Ohio, fair will offer a sensory-friendly morning for people with autism or other conditions that make them vulnerable to sensory overload, WOWK reports.

State fairs are normally filled with flashing lights, screaming children, and loud music—all factors that could be overwhelming for some people on the autism spectrum. That means many kids and their families are forced to stay home and miss out on what would otherwise be a fun experience because of the potential for sensory overload.

This summer, extra-sensitive guests will have an opportunity to attend the fair in a safe, inclusive environment. The Ohio State Fair teamed up with OCALI (the Ohio Center for Autism and Low Incidence) to remove or reduce any potential sensory triggers. Rides will run without the regular loud music and flashing lights, and if riders ever feel overwhelmed, they can take a break in the fair's air-conditioned quiet room. There they'll find low-tech and mid-tech activities, like fidget devices, that they can use to wind down.

Another way families can help kids with autism feel more comfortable at the fair is by preparing them for the trip. OCALI has written up a document that caretakers can use to walk their children through the day ahead, with full-color photos to illustrate each attraction. Anyone can access it for free here [PDF].

This year's fair in Columbus will follow the example of several other fairs and amusement parks that have made their attractions more inclusive for autistic guests in recent years. The State Fair of Texas offered its first sensory-friendly morning in 2018, and Sesame Place in Pennsylvania recently became a certified autism center.

The 2019 Ohio State Fair opens on July 24 and will run through August 4.

[h/t WOWK]

What Is the Difference Between Heat Exhaustion and Heatstroke

YuriS/iStock via Getty Images
YuriS/iStock via Getty Images

When temperatures begin to climb, many of us can find ourselves growing physically uncomfortable. Indoors or out, warm weather can make us lethargic, sweaty, and nostalgic for winter. There are differences, though, between heat exhaustion—a precursor to more serious symptoms—and heatstroke. So what are they? And how can you treat them?

Heat exhaustion happens when the body begins to overheat as a result of exposure to excessive temperatures or high humidity. (Humidity affects the body's ability to cool off, because sweat cannot evaporate as easily in humid weather.) Sufferers may sweat profusely, feel lightheaded or dizzy, and have a weak or rapid pulse. Skin may become cool and moist. Nausea and headache are also common. With heat exhaustion, it’s necessary to move to a cooler place and drink plenty of fluids, though medical attention is not often required.

If those steps aren't taken, though, heatstroke can set in. This is much more serious and involves the body reaching a dangerous core temperature of 104°F or higher. People experiencing heatstroke may appear disoriented or confused, with flushed skin and rapid breathing. They may also lose consciousness. While heat exhaustion can be treated and monitored at home until symptoms resolve, heatstroke is a medical emergency that requires prompt attention by a health professional. Until help arrives, heatstroke should be treated with cool cloths or a bath, but sufferers should not be given anything to drink.

Although young children and those over the age of 65 are most susceptible to heat-related health issues, anyone can find themselves having a reaction to warm temperatures. If you’re outside, it’s best to drink plenty of fluids, wear light-fitting clothing, and avoid being out in the afternoons when it’s warmest. Because sunburn can compromise the body’s ability to cool itself, wearing sunscreen is also a good idea.

While it’s not always possible to avoid hot or humid weather, monitoring your body for symptoms and returning to a cool space out of the sun when necessary is the best way to stay healthy. If you have older relatives who live alone, it’s also a good idea to check on them when temperatures rise to make sure they’re doing well.

[h/t WWMT]

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