What Are the Common Causes of Hives?

Hive Aren't Always Caused by Allergies

Urticaria
konmesa/istockphoto

Urticaria, or hives, is a dermatologic condition that causes swollen, red bumps on the skin. Also known as weals, these bumps usually appear rapidly and can be anywhere on the body, causing your skin to itch, burn, or sting.

The itching is often the worst part and once you've gone through it, the idea of reliving the experience is unpleasant. That's why you might be desperate to know what caused it.

Allergies to foods and soaps or detergents are often the first things that come to mind. While many people try to avoid these suspected triggers, they frequently find that it doesn't help. You might be surprised to know that while allergies may be the problem, other causes are more common.

What Caused Your Hives?

Urticaria affects almost 20 percent of the population but the majority of the time, the cause is unknown (idiopathic). Even so, it is a good idea to try to find the trigger so you can possibly avoid it in the future.

The causes of hives can generally fall into one of three categories:

  • Idiopathic - There is no known cause.
  • Immunological - Caused by a change in your immune system.
  • Nonimmunological - Caused by exposure to a substance that doesn't affect your immune system.

Whether tied to the immune system or not, exposure to a trigger causes mast cells (a type of white blood cell) to release histamine.

This, in turn, can cause the weals to form on the surface of your skin. 

Hives can further be categorized by how long they last. Acute hives last for less than six weeks; chronic hives can last longer. In many cases, a trigger that causes acute hives is not the same as what causes chronic hives.

Viral Infections

The most common cause of acute hives, particularly in children, is a viral infection such as an upper respiratory infection.

This may be true even if a child has not had any obvious illness recently.

Acute hives can be related to other infections such as strep throat, athlete’s foot, mononucleosis, and coxsackie viruses. Though they're not viral infections, both intestinal worms and malaria can also cause urticaria.

Allergic Reactions

Allergic reactions, particularly to foods and medications, are another common cause of acute hives. Allergies only cause about 5 percent to 10 percent of chronic hives cases. Pet allergies are usually to blame; pollen, mold, and dust mite allergies cause chronic hives only in rare instances.

Generally speaking, acute hives that occur as a result of eating certain foods appear within a few minutes to a few hours of eating the food. Reactions to medications may occur after the first dose, or not until it has been taken for a week or two.

Food allergies that cause hives can include anything that you're allergic to. The most common suspects are milk, nuts, peanuts, and shellfish. Less common allergies such as cheese, chocolate, eggs, garlic, melons, pork, spices, strawberries, and tomatoes may also be responsible.

Likewise, food allergies can extend into additives that are commonly found in processed foods.

Among the known triggers are benzoates, citric acid, eggs, fish albumin, penicillin, salicylates, sulfites, tartrazine (dye), and yeast.

Yet another consideration is if you have an allergy to latex because a number of foods are known to produce a cross-reaction. Foods on this list include avocado, bananas, chestnuts, kiwi, and passion fruit.

Stress

Stress is one cause that acute and chronic hives share. You may not feel particularly stressed, but your body may, especially if you are very busy. Keep in mind that life stressors may be either positive or negative. Your approaching wedding day may be as much to blame as trouble at work, for instance.

Chronic Infections

Chronic infections such as viral hepatitis, sinus infections (sinusitis), and urinary tract infections can cause chronic hives. An infection with Helicobacter pylori, a bacteria commonly connected with stomach ulcers, is also associated with chronic hives. 

Metabolic Diseases

Metabolic diseases, such as low or high thyroid function, liver disease, and kidney disease, may also be at the root of chronic hives.

In addition, it appears that a large percentage of people without an obvious trigger for chronic hives may actually have an autoimmune disease. With these conditions, the immune system attacks healthy tissue, including the skin. Juvenile rheumatoid arthritislupus, and dermatitis herpetiformis (associated with celiac disease) are among those that may cause hives.

Other Medical Conditions

The skin is the body's largest organ, so it's not uncommon for a variety of other medical conditions to affect it and this may result in hives. For instance, people with cancers like lymphoma may be prone to hives, as are those dealing with carcinomas (skin cancer).

Additionally, inflammatory diseases like rheumatic fever can affect the skin, as can pemphigoid, a rare rash that appears during pregnancy. A rare disorder, mastocytosis involves the mast cells, which are connected to allergies. Hives may also be caused by amyloidosis, polycythemia vera (bone marrow), or cholecystitis (gallbladder).

Medications

Beyond allergic reactions, some medications are also associated with chronic hives. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most notable, so your reaction could be due to something as common as aspirin. Antibiotics, codeine, morphine, and radiocontrast dye are also known to be triggers.

More

Getting to the bottom of what caused your hives is not easy and it's possible that you may never know. However, it's also likely that you can check many of these known causes off your list of potential triggers. Since most cases have no known cause, what is important is properly treating hives, which is typically done with done with antihistamines.

Source:

Griffiths C, Barker J, Bleiker T, Chalmers R, Creamer D. Rook's Textbook of Dermatology, 4 Volume Set. 9th ed. West Sussex, UK: John Wiley & Sons; 2016.

Jafilan L, James C. Urticara and Allergy-Mediated Conditions. Primary Care. 2015;42:473-83.

Continue Reading