mosquito on hand
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Bug Bites

Most insect stings and bites cause some kind of redness, swelling, or itching. Sometimes, they bring more than a small bump. Hives happen when your whole body has an allergic reaction.

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woman sick in bed
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Watch out for hives when you have bacterial or viral problems, such as:

  • Hepatitis
  • HIV
  • Cytomegalovirus
  • Epstein-Barr virus

Even the common cold can sometimes set off a hive reaction.

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arm with welts that spell dermatographia
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Take your nail and firmly (but not too firmly) scratch a line into your skin. If the raised mark it makes sticks around for half an hour, you’ve got something your doctor may call dermatographism. It's hives that pop up from rubbing or scratching your skin.

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sweaty man
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Working Out

When you exercise, your temperature goes up. Warm, flushed skin is the perfect host for a hive party.

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woman stressed at work
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When you’re under pressure, your hormones surge. That puts your body into something called fight-or-flight mode. It can set off a host of reactions, including hives.

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alcohol variety
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Did you know you could be allergic to alcohol? Alcohol intolerance can cause a flushed face, nausea, vomiting, diarrhea -- and hives.

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foods that cause allergies
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What you eat can bring hives. Things like shellfish, peanuts, tree nuts, certain fruits, and milk are all common culprits. 

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medication bottles
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Just about any drug can cause hives. You could see red, itchy welts after doses of:

  • Penicillin
  • Aspirin
  • Ibuprofen
  • Naproxen
  • Blood pressure meds
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man with tight backpack strap
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A Tight Squeeze

Squeezed skin can bring welts called pressure hives. Any kind of force can cause them, including:

  • A heavy backpack on your shoulder
  • A waistband with no give
  • Sitting in a hard chair for too long
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woman under umbrella
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It’s rare, but you can be allergic to sunlight. When this reaction happens, you get hives only on the parts of your skin the sun has touched.

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woman in jaccuzi
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Hives thrive on warmth. Anything that makes you hot can be a trigger, like:

  • Hot baths
  • Blushing
  • Sunburn

If your temperature’s up, the welts can come out.

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woman in parka
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Any contact with lower temperatures -- from a blast of winter air to a dip in a pool -- can bring on your rash.

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scientist with blood test
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Autoimmune Disease

Often, hives happen because your immune system is too active. Your body’s defenses attack normal tissue, and boom -- breakouts.

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woman holding bandage
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Disposable gloves, bandages, condoms, pacifiers, balloons, shoes -- the list of things made of latex is long. Everything on it can cause hives, if you’re allergic. Usually, it’s the protein in natural-rubber latex that riles things up.

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cat and brush with dander
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Dander can drum up hives quickly. So can saliva from cats and dogs. If you notice red welts after petting or playing with a furry friend, your playmate is probably the cause of your blotches.

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Sources | Medically Reviewed on 12/19/2019 Reviewed by Hansa D. Bhargava, MD on December 19, 2019


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American Academy of Dermatology: “Hives.”

American College of Allergy, Asthma & Immunology: “Hives (Urticaria),” “Pet Allergies,” “Latex Allergy.”

American Family Physician: “Exercise-Induced Anaphylaxis and Urticaria.”

American Osteopathic College of Dermatology: “Urticaria,” “Dermatographism.”

Asthma and Allergy Foundation of America: “Insect Allergies.”

Kids Health: “Hives (Urticaria).”

Mayo Clinic: “Alcohol Intolerance,” “Sun allergy,” “Hives and angioedema.”

NHS Choices: “Urticaria (Hives) - causes,” “Struggling with Stress?”

Reviewed by Hansa D. Bhargava, MD on December 19, 2019

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.

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