First things first, what exactly are allergies? An allergy is when your immune system reacts to a foreign substance, called an allergen, as though it is harmful. This can be something that you eat, touch, inhale or inject in your body.

The tendency to develop allergies is often hereditary, which means it’s passed down from parents who have allergies or closely related conditions, such as asthma or eczema. However, a family history of allergies does not guarantee that someone will have them. And particular allergies aren’t typically inherited — it’s just the likelihood of having allergies.

About 50 million Americans have some type of allergy — that’s about 15% of the population. According to the American College of Allergy, Asthma & Immunology, allergies are the sixth-leading cause of chronic illness in the U.S.

Many people believe that allergies are something people develop as children and outgrow, but many kinds of allergies can be lifelong or develop in adulthood. Most children don’t outgrow seasonal allergies, which can also emerge or worsen with age. While children are likely to outgrow certain food allergies, recent research from the American College of Allergy, Asthma & Immunology actually found that 45% of adults with food allergies developed them in adulthood.

People can be allergic to everything from foods to plants and animals to medicine and household chemicals. According to the Asthma and Allergy Foundation of America, the most common food allergies are peanuts, milk and shellfish, while the most common indoor/outdoor allergens are trees, grass and weed pollen, mold spores, dust mites, cockroaches and animal dander.

It might seem like fiction, but people can be allergic to things such as water, sunlight, exercise and physical touch. Some of these health conditions are extremely rare. For example, water allergy, or aquagenic urticaria, affects only one in every 23 million people. However, some are more common than you might think — about one in every 1,000-2,000 people is allergic to exercise.

Seasonal allergies, also known as "hay fever," are triggered when molds release their spores, and trees, grasses and weeds release pollen into the air. What time of year you experience symptoms could reveal what you’re likely allergic to. For example, in the United States, tree pollination typically begins earlier in the year, while grass pollination takes place later in the spring and summer and ragweed pollinates in the late summer and fall.

Don’t write off seasonal allergies as something to just suffer through. According to the American College of Allergy, Asthma & Immunology, more than two-thirds of spring allergy sufferers actually have year-round symptoms. If you have persistent symptoms that are interfering with your everyday life or feel like you’re constantly getting sick, it might be time to see an allergist to get to the root of your problems.

Many common allergy symptoms are also symptoms of other illnesses, such as the cold, the flu and even COVID-19. However, allergy symptoms are chronic and shift based on your environment. These symptoms tend to improve with antihistamines or other allergy-specific medications. A runny nose or itchy eyes aren’t typical of the coronavirus and likely indicate allergies. On the other hand, seasonal allergies also do not cause a fever, chills, body aches, exhaustion, diarrhea or vomiting, which are some of the key symptoms of coronavirus.

A common myth that seasonal allergy sufferers hear is that they should move to a different climate, especially a dry or desert climate, to “fix” or “cure” their allergies. However, moving away from the source of your allergies will likely only bring temporary relief. Some common seasonal culprits such as grass and ragweed pollens are present nearly everywhere — they can travel for hundreds of miles. And your new environment could contain new plants or other allergens you didn’t even know you were allergic to.

A diet trend that’s emerged over the years to address a variety of concerns is cutting specific foods or food groups, such as gluten and dairy, from your diet. However, eating or avoiding certain foods has no proven effect on seasonal allergies. According to the Australasian Society of Clinical Immunology and Allergy, eliminating things like wheat and milk from your diet will only help your allergy if you are allergic to wheat and milk.

If you are allergic to animals, such as cats or dogs, continuous exposure will not decrease your allergy. However, recent studies suggest that pet exposure in early childhood could have beneficial effects and prevent the development of an allergy.

The most common way to test for allergies is using a skin test, which can check airborne, food-related and contact allergens. There are three types of skin tests: scratch, intradermal and patch tests. Each of these methods exposes the body to different allergens to see how it reacts. Blood tests can also be used. A doctor will take a blood sample then test it for antibodies that fight specific allergens.

Unfortunately, there is no “cure” for allergies. The closest thing is a long-term treatment called allergen immunotherapy, which slowly desensitizes patients to certain allergens. Allergy shots are the most commonly used form of allergy immunotherapy.

One of the most effective strategies for treating allergies is to avoid allergic triggers. But for those who do come into contact with allergens, there are medicines that can treat symptoms, including antihistamines, eye drops and nasal sprays. EpiPens, a type of epinephrine auto-injector, can be used in emergency situations to reverse the symptoms of anaphylaxis, reducing swelling and making it easier to breathe.

Symptoms of an allergic reaction vary widely and depend on the severity of the allergy and how much you come in contact with. Common symptoms of an allergic reaction include sneezing and an itchy, runny or blocked nose; coughing, wheezing and shortness of breath; itchy, red, watering eyes; a rash or hives; nausea, vomiting or diarrhea; and swelling of the lips, tongue, eyes or face.

Symptoms of allergies can range from minor nuisances to being potentially fatal. Exposure to certain allergens can cause a life-threatening allergic reaction known as anaphylaxis. This is most commonly a reaction to food allergies, insect sting allergies and allergies to medications or latex. While about 5% of U.S. citizens are estimated to have experienced anaphylaxis, only 1% of hospitalizations resulted in death, making it a rare cause of death according to a report published in the Journal of Allergy and Clinical Immunology.

Lactose is the sugar that's found in milk. When people have trouble digesting this sugar, it’s known as lactose intolerance. However, food allergies are triggered by protein in a food. Lactose intolerance isn’t a true food allergy, however, people can be allergic to milk. If you are lactose-intolerant, kefir is a milk alternative that’s also a great food for weight loss.

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