Photo of woman sneezing in flowering meadow
1 / 10

1. Your Overactive Immune System

Many things can trigger an allergic reaction. It happens when your body's defenses attack something that's usually harmless, such as pollen, animal dander, or food. The reaction can range from mild and annoying to sudden and  life-threatening. In the US, about 30% of all adults and 40% of children have allergies.

Swipe to advance
SEM Photo of Pollen on Sunflower Pistil
2 / 10

2. Pollen

It comes from plants such as grasses, trees, and weeds and can trigger hay fever or seasonal allergies. You might sneeze and have a runny or stuffy nose and itchy, watery eyes. Treat these with over-the-counter products, prescription drugs, and allergy shots. To help prevent symptoms, stay inside on windy days when pollen counts are high, close windows, and run the air conditioning.

Swipe to advance
Photo of brown dog on furniture
3 / 10

3. Animal Dander

You love your pet, but if you're allergic, you react to proteins in their saliva or in their skin's oil glands. It might take 2 years for that to start. Luckily, you may still be able to live with them. Make your bedroom a pet-free zone, opt for bare floors and washable rugs instead of carpets, and bathe them regularly. A HEPA filter and allergy shots may help, too.

Swipe to advance
Photo of dust mite scavenging through a dust ball
4 / 10

4. Dust Mites

These tiny bugs live in bedding, mattresses, upholstery, carpets, and curtains. They feed on dead skin cells from people and pets, as well as on pollen, bacteria, and fungi. They thrive in high humidity. To cut down on problems, use hypoallergenic pillows, cover mattresses, pillows, and box springs, and wash sheets weekly in hot water. Keep the house free of dust-collecting items such as stuffed animals, curtains, and carpet.

Swipe to advance
Photo of head of yellow jacket wasp
5 / 10

5. Insect Stings

These could cause swelling and redness that may last a week or more. You might feel sick to your stomach and tired and have a low fever. In rare cases, insect bites trigger a reaction that can be life-threatening, called anaphylaxis. If you're severely allergic, you'll need medicine called epinephrine right away. Your doctor may recommend allergy shots to prevent reactions.

Swipe to advance
microscopic image of common mold
6 / 10

6. Mold

It needs moisture to grow. You can find it in damp places such as basements or bathrooms, as well as in grass or mulch. Since breathing in mold spores can set off an allergic reaction, avoid activities that could trigger symptoms, such as raking leaves. Get air moving in moist areas of your home.

Swipe to advance
Photo of cluster of peanuts in shells
7 / 10

7. Food

Milk, shellfish, eggs, and nuts are among the most common foods that cause allergies. Others include wheat, soy, and fish. Within minutes of eating something you're allergic to, you could have trouble breathing and get hives, vomiting, diarrhea, and swelling around your mouth. If your reaction is severe, you will need emergency medical help. So call 911, and use your epinepherine pen if you were prescribed one. 

Swipe to advance
Photo of hands putting on latex gloves
8 / 10

8. Latex

Found in some disposable gloves, condoms, and medical devices, latex can trigger a reaction ranging from itchy, red skin to anaphylaxis with trouble breathing. Symptoms can include a rash or hives, eye irritation, runny or itchy nose, sneezing, and wheezing. If you’re allergic, wear a medical alert bracelet and carry an epinephrine kit if you were prescribed one.

Swipe to advance
Photo of spilled bottle of aspirin
9 / 10

9. Medication

Penicillin, aspirin, and other drugs can cause hives, itchy eyes, stuffiness, and swelling in your face, mouth, and throat. If you're allergic to a drug, it's best to not take it. Your doctor can talk to you about other medicine options or treatments that may allow you to take a medicine if it's necessary.

Swipe to advance
Photo of silhouetted cockroach crawling on fabric
10 / 10

10. Cockroaches

A protein in their droppings can be a trigger. Roaches can be tough to get rid of, especially in a warm climate or if you live in an apartment building where they can move back and forth between neighbors. Treat them with bug killer, and keep a clean kitchen. Repair cracks and holes in floors, walls, and windows to keep them out of your home.

Swipe to advance

Up Next

Next Slideshow Title

Sources | Medically Reviewed on 02/08/2020 Reviewed by Sabrina Felson, MD on February 08, 2020


(1) Altrendo images
(2) Susumu Nishinaga / Photo Researchers, Inc.
(3) Chris Amaral / Digital Vision
(4) David Scharf / Science Faction
(5) Charles Krebs / Science Faction
(6) Getty
(7) Food Image Source / StockFood Creative
(8) PhotoAlto / Ale Ventura
(9) M Stock - The Stock Connection / Science Faction
(10) iStockphoto



American College of Allergy, Asthma & Immunology: “Common Seasonal Allergy Triggers.”

American Contact Dermatitis Society.

Asthma and Allergy Foundation of America: “Dust Mite Allergy.”

Cleveland Clinic: “Problem Foods: Is It An Allergy or Intolerance?”

Johns Hopkins.

Food Allergy Research & Education: “Allergens.”

Reviewed by Sabrina Felson, MD on February 08, 2020

This tool does not provide medical advice. See additional information.

THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the WebMD Site. If you think you may have a medical emergency, immediately call your doctor or dial 911.