For Asthma and Allergy Awareness Month, this edition of the Medical Myths series tackles some of the many myths and misconceptions associated with allergies.
In brief, an allergy is an unusual or exaggerated immune response triggered by a particular substance. Symptoms often include itchy eyes, wheezing, and sneezing. For many people, allergic reactions are uncomfortable and unpleasant, but they can be life threatening for others.
According to estimates from the Centers for Disease Control and Prevention (CDC), up to 60 million people in the United States experience allergies each year.
The World Health Organization (WHO) estimates that around 20% of people worldwide have an allergic condition.
One of the most common allergies — hay fever — affected an estimated 19.2 million adults in the U.S. during 2018, and this figure is likely to rise.
“Allergies are currently on the rise in the U.S.,” explained Dr. Omid Mehdizadeh, an otolaryngologist and laryngologist at Providence Saint John’s Health Center in Santa Monica, CA.
He told Medical News Today that “scientists believe the increasing prevalence of environmental allergies is due to changing weather patterns and increasing pollen blooms in the U.S.”
Considering their prevalence, understanding and dismissing the myths associated with allergies is an important task. Here, we tackle 11 such myths.
One persistent myth is that once you reach adulthood, you don’t develop any more allergies. This is untrue.
One study, for instance, looked at the prevalence of food allergies in 40,443 adults in the U.S. At the time of the survey, 10.8% of participants had a food allergy.
The authors found that in around half of these individuals with food allergies, at least one of these food allergies developed during adulthood.
In general, the best way to minimize allergic reactions is to avoid triggers, whether a particular food or a type of animal. There are no cures for allergies.
However, certain treatments can effectively reduce the symptoms. For instance, decongestants can relieve the nasal symptoms of allergies, while antihistamines and nasal steroid sprays can also be effective.
“Immunotherapy involves giving gradually increasing doses of the substance, or allergen, to which the person is allergic. The incremental increases of the allergen cause the immune system to become less sensitive to the substance, probably by causing production of a ‘blocking’ antibody, which reduces the symptoms of allergy when the substance is encountered in the future.”
This is not true: food allergies and food intolerances are different. When someone experiences a food allergy, it is driven by their immune system, usually associated with the action of Immunoglobulin E (IgE).
During an IgE-mediated immune response, IgE binds to receptors on specific cells, including mast cells and basophils. These cells then produce histamine and other compounds, causing symptoms to appear very rapidly.
On the other hand, intolerances do not involve the immune system, and symptoms take longer to appear. And while intolerances are not life threatening, food allergies can be in some cases.
Thankfully, this is a myth. Although some allergies do persist for life, as Dr. Mehdizadeh told MNT, “Some allergies may simply dissipate with age.”
Whether an allergy diminishes over time can depend on the allergen. The authors of a review on food allergies explain:
“Although most children ‘outgrow’ allergies to milk, egg, soy, and wheat, allergies to peanut, tree nuts, fish, and shellfish are often lifelong.”
Although peanut allergies are common — affecting an estimated 6.1 million people in the U.S. — and can certainly be dangerous, there is no way to rank allergy severity. Some individuals might have only a mild reaction to peanuts but, for others, it could spark anaphylaxis.
Although certain foods, such as tree nuts, shellfish, and eggs, account for most allergies, virtually any food can trigger a reaction. The severity of the reaction depends on an individual’s immune system.
Although colds and allergies can share certain symptoms, including a blocked nose and runny eyes, they are different. Symptoms of a cold are caused by an immune response to viruses, while allergies are an immune response to an allergen.
Another important difference is that colds tend to last around 1–2 weeks, whereas allergies can, in some cases, last a lifetime.
This is not true. For some people, certain breeds may be less likely to trigger allergies, but there are no hard and fast rules. Allergies are not triggered by an animal’s hair — they are set off by dead skin cells (dander), saliva, and urine.
Many people believe that certain cat and dog breeds are “hypoallergenic,” meaning they do not trigger allergies. However, this is a myth. As the AAAAI explains:
“Contrary to popular opinion, there are no truly ‘hypoallergenic breeds’ of dogs or cats. Allergic dander in cats and dogs is not affected by length of hair or fur, nor by the amount of shedding.”
There is a common theory that if someone with an animal allergy spends time with that type of animal, the allergy will slowly improve. But this is not the case. In fact, some pet owners can gradually become allergic to their pets over time.
Dr. Mehdizadeh explained to MNT:
“Once the immune system is primed or sensitized to an allergen, for instance, a pet, an individual remains allergic if they are exposed to high amounts of pet hair or dander. The idea of immunotherapy or ‘allergy shots’ and desensitization only work under the guidance of an allergist, and when exposed to an allergen in small and gradually increasing amounts.”
A related point, outlined by the authors of a paper on pet allergies, is that “early introduction of pets at home may reduce the likelihood of developing” an allergy in the first place. In other words, if pets are brought into a home when children are young, they may be less likely to develop allergies to those animals as they age.
Thankfully, for many people, allergies are uncomfortable and inconvenient but not dangerous. However, for some individuals, an allergic reaction can culminate in anaphylaxis.
Anaphylaxis is a severe and, in some cases, life threatening allergic reaction. During this event, a large amount of histamine is released into the body, causing an inflammatory response.
Symptoms can include difficulty breathing, wheezing, stomach pain and cramps, diarrhea, anxiety, swelling of the feet, hands, lips, eyes, and sometimes the genitals, and loss of consciousness.
Even allergies that might be considered relatively minor, such as seasonal allergies, can cause significant issues. Hay fever can result in reduced quality sleep and, therefore, daytime sleepiness. In turn, this can make it more difficult to focus at work, increasing the risk of absenteeism or workplace accidents.
One 2012 study investigated the impact of hay fever on the “health-related quality of life” of 616 participants. They concluded that hay fever “impairs work productivity in a greater magnitude” than hypertension and type 2 diabetes.
Another study from 2009 investigated the broader effects of seasonal allergy, concluding that hay fever “has a significant negative impact on sexual function and can result in sleep disturbances and fatigue.”
Perhaps surprisingly, this is a myth. Hay fever, or allergic rhinitis, is caused by airborne pollen. Flowers tend to produce large, sticky pollen, which does not fly through the air easily — flowers are designed to attract insects and fasten pollen to their bodies rather than release it into the air.
The major causes of hay fever are lighter pollen from grasses and trees.
Allergies are surprisingly common, and they vary from relatively minor to life threatening. It may be because of this prevalence and variety that so many myths are associated with them. Their counterintuitive nature might also play a part — after all, why should one’s immune system react to a peanut or a pooch?
Although there is still no cure for allergies, scientists continue their voyage of discovery. One day, they will surely find a way to blunt their impact on the world’s populations.