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What are the most common allergic reaction symptoms?

Symptoms of an allergic reaction can range from mild, localized flare-ups in a specific part of your body to severe allergic reactions that set off alarm bells throughout your body. Here’s what to look out for.

Congestion, sneezing, and a runny nose

When you breathe in an allergen like tree pollen, mold, or dust, your immune system triggers the release of histamines from cells inside your nasal passageways, Dr. Abdeldaim says. This causes “allergic rhinitis,” or inflammation in your nose, and in turn an uptick in the production of mucus. Seasonal and year-round allergens alike can trigger an itchy, stuffed-up nose, sneezing attacks, and postnasal drip (that uncomfortable sensation as mucus from your sinuses trickles down your throat).

You might feel like you just have the common cold, Dr. Tam says. But one way to tell the difference is that a viral infection typically clears within one to two weeks, whereas allergy symptoms are chronic and could last for several weeks.

Itchy, irritated eyes

If allergens like pet dander or dust mites make their way into your eyes, histamines could flare up and make them swollen, red, itchy, and watery, Marc F. Goldstein, MD, a board-certified allergist and immunologist at The Asthma Center in Philadelphia, tells SELF. This is called allergic conjunctivitis because allergens cause the protective covering of the eye and eyelid—the conjunctiva—to swell. Your eyes might also feel like they’re burning or more sensitive to light.

A rash

The release of histamine can also make your skin itchy, Sanjeev Jain, MD, PhD, a board-certified allergist and immunologist at Columbia Allergy in California, tells SELF. In fact, irritated skin is one of the most common signs of an allergic reaction whether you’ve eaten, inhaled, or brushed up against an allergen.

Symptoms can vary. You may develop dry, itchy patches due to eczema after your skin’s been exposed to an irritant or allergen, or you could have itchy, red bumps or hives.

Trouble breathing, coughing, and wheezing

If histamines make their way to your lungs, they could also trigger asthma symptoms like shortness of breath and coughing fits, Dr. Tam says. If you’re one of over 25 million Americans with asthma, allergens (like cockroaches, pet dander, mold, and dust mites) are also one of the most common triggers for trouble breathing and wheezing. Even food allergies can cause asthma-like symptoms.

Gastrointestinal distress

Within minutes, even a small amount of food—like a sip of milk, traces of eggs, or peanuts—could trigger an allergic reaction in your G.I. tract. Inflammation in your stomach could cause symptoms like cramping, nausea, vomiting, abdominal pain, and even diarrhea, Dr. Goldstein says.

It’s easy to confuse food allergies with food intolerances. But food intolerances tend to be limited to G.I. issues while food allergies often come with additional symptoms like tingling or itching in your mouth, swelling in your mouth and throat, itchy skin, hives, wheezing, nasal congestion, trouble breathing, and even dizziness and fainting.


Finally, one important cluster of symptoms to be aware of is anaphylaxis, Dr. Tam says. This severe allergic reaction is life-threatening, so immediate emergency medical attention is a must. Anaphylaxis is most commonly caused by foods, insect stings, medications, and latex allergies.

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