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Common Triggers for Hives and When to Get Help

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It starts as a mindless tickle on the side of your neck. You find yourself itching the spot casually. A few minutes later, you’re rubbing your side along your ribs with more persistence, moving to scratch the back of your hand next. You look down and recognize, in a second, the telltale sign of a larger issue than just an itchy sweater or pesky few mosquito bites.


The unsightly red, itchy spots are noticeably appearing like unwanted house guests, and you feel helpless and desperate for relief. If you’ve ever developed an allergic reaction to a food item or an insect that has resulted in a hive breakout on your skin, then you know all too well the discomfort and stress of these little red spots. What causes hives, and if you’re susceptible, how can you avoid them? More importantly, when is the appearance of hives the first indication of a potentially dangerous allergic reaction, and when should you receive urgent treatment?

What are Hives?

Urticaria, or hives, are a skin rash that appears as welts or raised bumps on the skin. They are often red and uncomfortably itchy. They can range in size from small to large bumps, up to 8 inches in diameter at their largest, and may appear on one body part or all over the skin. When you press on a hive, it will appear white in the middle. Like their size, the duration of an outbreak of hives may vary as well. For some patients, hives may appear for a few minutes or last for several months, with most people experiencing hives finding them to last at least 24 hours.

What are the Most Common Causes of Hives?

Anyone at any age can develop hives if exposed to an irritant that causes an autoimmune response in the body. About 20 percent of people will develop hives at least once in their lifetime. The most common triggers of hives include:

  • Infections, including the common cold and other viruses
  • Food allergies, most commonly including eggs, shellfish, and nuts
  • Medications, such as aspirin, antibiotics such as penicillin, and sulfa
  • Insect stings or bites
  • Blood transfusions
  • Other autoimmune conditions, such as thyroid disease

Some patients experience chronic episodes of hives that can last over six weeks. In these cases, doctors cannot always determine the underlying cause of the outbreak.

Another form of hives is dermatographia, a condition in which light scratching of the skin causes raised, uncomfortable red lines at the scratch site. Delayed pressure urticaria occurs when skin under constant pressure, such as from constrictive clothing, swells and becomes irritated.

Other hive triggers may include:

  • Exposure to low temperatures followed by re-warming—a potentially life-threatening situation if there is a generalized body cooling
  • An increase in body temperatures during exercise, a hot shower, or an anxiety-inducing situation, known as cholinergic urticaria
  • Sun-exposure

When to Seek Urgent Medical Care?

Hives can often be treated with a topical or oral antihistamine medication. However, in more severe cases, hives are one symptom that appears during anaphylaxis. This potentially dangerous allergic reaction can cause swelling of the tongue or throat and difficulty breathing. If anaphylaxis occurs, call 911 immediately. If your doctor diagnoses you with a severe allergy to a specific food or other substance, they may prescribe you an epinephrine pen which can be administered during a severe allergic reaction to immediately abate swelling that can make it difficult to breathe.

Otherwise, if you often experience hives that do not cause respiratory issues and you believe you may be allergic to a food item or medication, talk to your doctor. They can conduct tests to help you identify the cause of your outbreaks. If you are experiencing chronic urticaria, your doctor may refer you to an allergist or immunologist for more specialized testing and treatment.