This article explains the basics of an allergic reaction. Learn what happens when your immune system goes on high alert.

Anyone can get them, at any age. You could develop them as a child, or you might not have any symptoms until you’re an adult.

While your problem may seem to start in the nose or the eyes, allergies actually come from an immune system run wild.

Worsening of asthma symptoms can be triggered by allergies, which can temporarily increase the inflammation of the airways.

Sinusitis is an inflammation or swelling of the tissue lining the sinuses. Allergies can trigger sinusitis.

It's not common, but sometime allergies can cause a life-threatening reaction called anaphylaxis.

Nasal polyps are noncancerous growths that form in the nose or sinuses. They’re often linked to allergies or asthma.

Dupixent contains dupilumab that helps to reduce the swelling and irritation in people with CRSwNP.

There's no cure but you can take steps to curb springtime allergies, from medication to household habits.

Summer allergies are usually triggered by pollen from grasses and weeds.

Ragweed, mold, and dust mites are the biggest allergy triggers in the fall.

With indoor allergies such as mold and dust mites, you may notice symptoms more during winter, when you spend more time inside.

Hay fever, or allergic rhinitis, is an immune disorder presented by an allergic response to pollen grains and other substances.

All of us are exposed to some mold every day, usually, without problems. If you have allergies to it, you can have a reaction.

For creatures you can't even see, dust mites can stir up a lot of trouble.

For a person with dog allergies, life in a dog-loving country isn't easy. Roughly 37%-47% of American households have a dog.

About 10% of the U.S. population has pet allergies, and cats are among the most common culprits.

Food allergies or food intolerances affect nearly everyone at some point.

Xolair can make it less stressful and less dangerous to have serious food allergies.

If you have a milk allergy, avoiding milk and food containing milk and milk products is the only way to prevent a reaction.

If a glass of milk or slice of pizza causes swollen lips, hives, or other symptoms, you may have an allergy to casein.

Egg allergies are more common in children than in adults. Reactions range from mild to severe.

It can be a challenge to avoid wheat because it’s in so many things.

If you have a nut allergy, avoiding nuts, including peanuts and tree nuts, and food with nuts is the way to prevent a reaction.

If you’re allergic to one kind of seafood, your doctor may have told you to avoid others. Here’s what to look out for.

Sulfites are a group of sulfur-based compounds that may occur naturally or may be added to food as an enhancer and preservative.

A soy allergy is when your body reacts to soy protein. Soy protein is a product of soybeans and it’s in many foods.

Hives are swollen bumps, patches, or welts on the skin that appear suddenly. They happen because of allergies or other reasons.

Poison ivy, poison oak, and poison sumac are plants that contain an irritating, oily sap called urushiol.

Bee, wasp, yellow jacket, hornet, or fire ant stings are the insect stings that most often trigger allergies.

Polymorphous light eruption (PMLE) is a condition in which you get skin rashes even after limited sun exposure.

Certain ingredients in cosmetics, such as fragrances and preservatives, can act as allergens and trigger an allergic reaction.

A nickel allergy is a skin reaction that develops after exposure to nickel or items containing the metal.

Millions of Americans have allergies. Most of those millions have symptoms involving their eyes.

Many medications can cause side effects, and certain ones can trigger allergies.

If you're allergic to chemicals called salicylates, you may need to avoid certain foods, medicines, and other products.

Penicillin has been a go-to drug to clear up bacterial infections. But some people get a bad reaction from taking it.

An allergist may be able to help identify your allergy triggers. Several different types of allergy tests are used to do this.

If you think you have allergies, think about seeing a doctor who can tell you whether you do or not.

Skin testing is one way your doctor can check on what causes your allergy symptoms.

Allergy blood tests detect and measure the amount of allergen-specific antibodies in your blood.

Food allergies are common -- and commonly misunderstood by doctors as well as patients.

If you have a food allergy, you may need to keep a diary – and remove foods from your diet – to isolate what you’re allergic to.

An elimination diet involves removing specific foods or ingredients from your diet that you may be causing your allergy.

Learn all about the different over-the-counter and prescription medicines that can help ease annoying symptoms.

When medicine is needed to stem allergy symptoms, antihistamines are often first in line.

When allergies make your nose stuffed up, an antihistamine generally won't help. But a decongestant might.

When allergies strike, nasal sprays can help. There are many different types, and most work faster than pills.

Allergy eyedrops are liquid medicines used to treat symptoms of eye allergies.

Montelukast (Singulair) is a drug that relieves allergy symptoms and is also used to prevent asthma attacks.

Allergy shots are one form of immunotherapy for allergies. You get the shots in a doctor’s office.

Natural treatments can't replace allergy medications, but they can work alongside them.

Medicines help treat allergy symptoms once they strike. But these easy steps can help you avoid having an attack.

Mold, mildew, and dust mites don’t have to make you miserable. A home dehumidifier can help you breathe again.

Special mattress and pillow covers can protect against dust mites, microscopic creatures that can trigger dust allergies.

Food allergies can be serious, but you can manage them. One of the best things you can do is avoid your trigger foods.

Whether you're newly diagnosed with chronic sinusitis with polyps or already in treatment, learn how to make the most of your doctor appointment.

Whether your child is newly diagnosed with a food allergy or you have questions about their current management plan, learn how to make the most of your doctor appointment.