Hives, also known as urticaria, affect about 20 percent of people at some time during their lifetime. Hives can start as itching, followed by swollen, red welts. The itching may be mild to severe. Scratching, alcoholic beverages, exercise, and emotional stress may worsen the itching. Hives symptoms can come and go, lasting minutes, hours, days, several weeks, months, or even years.

There are two types of hives, depending on how long they last:

Acute urticaria: hives that last six weeks or less

Chronic urticaria: hives that last or recur for more than six weeks

In general, the causes of acute and chronic hives are very different.

Acute urticaria last six weeks or less and are generally caused by the following:

• Foods and additives, especially peanuts, eggs, nuts, seeds and shellfish
• Medications such as aspirin and antibiotics (especially penicillin and sulfa)
• Insect stings or bites
• Blood transfusions
• Infections including the common cold, urinary tract infections, strep throat, infectious mononucleosis, hepatitis, or other viral infections

In most of these cases, the hives resolve when the cause is avoided, removed or treated.

Chronic urticaria last more than six weeks. In many cases, the cause of chronic hives cannot be identified despite detailed history and testing. This condition is called chronic idiopathic urticaria. The immune system is the cause of about 50 percent of hives that are not identified. In a minority of cases, chronic hives may be associated with thyroid disease, other hormonal problems, or rarely cancer. In most cases, chronic hives will gradually disappear over time.

One type of chronic hives is “physical urticaria” in which hives can have one or more physical causes. These
may include:

• Rubbing or scratching (dermographia). This is the most common reason for chronic hives. These physical hives appear within a few minutes along the path of rubbing or scratching and last less than an hour.
• Constant pressure (pressure urticaria).
• Change in temperature.
• Sun exposure (Solar urticaria).
• Inflammation of the blood vessels, called vasculitis, can also cause hives.

What is the treatment for hives?

In most instances, hives will improve with antihistamines. Low-sedating or non-sedating antihistamines are preferred. They are effective, long-lasting (may be taken once a day), with fewer side effects. Severe episodes of urticaria may require temporary treatment with an oral steroid medication. An immune modulator
called Xolair has also been recently approved for the treatment of chronic idiopathic urticaria. Speak to your allergist about whether this is the right medication for you. If your hives rash involves swelling of the tongue or lips, or includes trouble breathing or other systemic reactions, an epinephrine self-injector may be prescribed for you to carry.

What can trigger hives?

If the cause of hives can be identified, the best treatment is to avoid or eliminate it.

Foods: If a problem with a specific food is strongly suspected, then you should not eat that food. This will require you to carefully read packaged food labels and question restaurant staff about ingredients in meals.
Medications: If you have a problem with a specific medication, stop taking it and notify your doctor and your pharmacist.
Rubbing or scratching: Avoid harsh soaps and tight clothing. Frequent bathing followed by moisturizer may reduce the problem of dry skin, which can cause itching and scratching that can aggravate this condition.
Sun exposure: Wear protective clothing and apply sunblock when outdoors.
Pain Medications: High-dose pain medications such as non-steroidal anti-inflammatory drugs can often trigger an outbreak of hives.
Alcohol: Drinking alcohol can trigger an outbreak of hives.
Heat: Shower or bathe at the lowest temperature that you can tolerate.