What are hives?
Hives are red, itchy welts or swellings on the skin that often come in clusters. They sometimes have a light red or pale center surrounded by a darker red area around the borders -- a marking resembling tiny bull's eyes -- but may simply look like large red circles. In doctor speak, hives are known as "urticaria."
Hives can appear anywhere on the body, cropping up either in one small area or covering large patches of skin. They most often occur as part of an allergic reaction. No one lesion lasts more than 24 hours, but new ones may continue to appear until the condition resolves. Up to a quarter of Americans will get hives at least once in their lives.
Although hives can be highly uncomfortable to have, they are relatively harmless. Hives usually appear suddenly and go away on their own in a matter of days, hours, or even minutes. Chronic hives, however, can last for six weeks or more. Certain people have recurring outbreaks of hives for months or even years, and it's sometimes difficult to pinpoint the exact cause.
What causes hives?
When an irritant comes into contact with your body, your immune system sends chemicals, including histamine, to fight it. The sudden spike in histamine levels can cause an outbreak of hives in the upper layers of the skin. Hives are often caused by a hypersensitivity to:
- Foods (commonly eggs, shellfish, nuts, berries, dyes, or other additives)
- Drugs (any drug can touch off an allergic reaction, although allergies to penicillin, sulfa, and aspirin are especially common)
- Pollens and plants (nettles, poison ivy, poison oak, and so on)
- Animal fur
- Insect bites or stings
- Exposure to heat, cold, or sunshine
- In young children, a viral infection like a cold may trigger a bout of hives. Other potential triggers include physical exertion or exercise, stress, illness, chemicals, cosmetics, textiles, and pressure from materials rubbing against the skin.
When should I call the doctor?
Hives are a nuisance, but are not usually dangerous. Still, in some cases hives can be a serious, even life-threatening condition. An allergic reaction could quickly affect your ability to breathe, so call 911 or go to an emergency room immediately if you have hives accompanied by hoarseness or wheezing, swelling in your tongue or face, tightness in your throat, fainting, or if you develop hives on your tongue. You may need immediate medical attention if you experience cold sweats, nausea, dizziness, or trouble breathing after a bee sting, an insect bite, eating a meal, or taking medicine.
What if I develop hives after taking medication?
Hives that have a sudden onset and spread quickly after you've taken a medication mean that you've probably developed an allergy to that drug: Stop taking it and call your doctor for advice immediately. If it's clear that the medication is the cause, your doctor will most likely want you to replace it with another. He or she will also likely advise you to take an over-the-counter antihistamine such as Claritin to reduce the allergic response; depending on your symptoms, he or she may ask that you come in for immediate treatment as well.
In the case of a severe allergy, hives sometimes signal the onset of an allergic shock reaction that could cause your airways to swell, resulting in suffocation. Call 911 or have someone drive you to the emergency room immediately if you have trouble breathing or if you develop swelling in your eyes, lips, or throat.
What should I do if I develop a severe allergic reaction?
If you have a life-threatening allergy to a food, medication, or insect sting, wear a medical identification bracelet that describes your allergy. Also, make sure those around you -- coworkers, schoolteachers, family members, and medical providers -- know about your condition and how to treat it.
Your doctor may advise you to keep on hand a shot of an "anti-shock" kit that contains an antihistamine (such as Claritin or Zyrtec) and a drug called epinephrine, also known as adrenaline, to counter an allergic response. This prescription medication is available in a self-injection pen, known as an epi-pen, that you'll need to carry with you at all times.
If you're with someone who is in allergic shock, you may need to give the injection. If so, read the directions in the kit before giving the needle. One cautionary note: Don't give epinephrine to someone who has heart trouble.
Anyone who keeps an epi-pen on hand should also consider having an antihistamine along with it to try first. Sometimes it will be all that's needed to counter a mild reaction. The American Academy of Allergy, Asthma and Immunology advises that while antihistamines may be used together with epinephrine to treat severe allergic reactions, they should never be used instead of epinephrine because they can't reverse many of the allergy's most serious symptoms, such as a drop in blood pressure. However, Benadryl comes in tablets or capsules, so it doesn't work very quickly. If you are having a severe or life-threatening reaction and need help fast, the epi-pen is quicker.
How do you treat ordinary, run-of-the-mill hives?
Comfort is the main goal of treatment, since most hive outbreaks are relatively minor and short-lived. Wear loose cotton clothing. To soothe itchy skin, try cold compresses, a cool shower, or a tepid bath with a few tablespoons of baking soda or uncooked oatmeal thrown in. Try an over-the-counter antihistamine to reduce your body's response to the irritant and to relieve pain. Ask your doctor if you should take antihistamine pills.
If a large area of your body is affected, soak in a cool bath. Make a paste of three teaspoons of baking soda to one teaspoon of water and rub it on to relieve itching. This paste may also be helpful for hives resulting from insect stings.
Make sure to keep your fingernails trimmed and avoid scratching at your hives, which can make things worse. Since stress may also exacerbate hives, relax with a book, music, or a video, or try yoga or meditation to get rid of tension. Keep strenuous activity to a minimum until the hives go away, as exercise can trigger more defense reaction in the skin.
For people with chronic hives, the simpler treatments may not keep outbreaks under control. Typically, chronic hives go away on their own, whether you treat them or not. About half of all chronic cases clear up within a year, though some cases can take as long as five years. A very small percentage of people are plagued by hives for even longer. Rarely, in cases of extremely severe hives, your doctor may recommend stronger medications such as oral steroids (prednisone) to control eruptions. Doctors are cautious about prescribing these drugs, however, because of side effects associated with prolonged use.
What can I do to prevent hives?
Most people do not need to worry about hives, but some people with recurring problems should take special precautions.
Eliminating foods or other triggers that cause you to break out is the key to preventing hives. If you don't know what causes your hives, keep a diary of what you eat as well as what you do each day and what medications and other products you use. Allergy testing can also be helpful.
To track down unknown culprits, try eating foods for a few days that you think are safe for your body. Then slowly add other foods back into your diet, watching for any reaction signs. Read labels when buying food, and ask about "hidden" ingredients when eating out. Many foods contain hidden nut ingredients that aren't listed first on the label. Food allergies, especially milk and soy allergies, are a particular problem for infants and young children. But the good news is that many people eventually outgrow these allergies.
If you like being outdoors, try to wear long-sleeved clothes and long pants to avoid insect bites. Keep food covered to prevent attracting bees or wasps. Wear closed-toe shoes and avoid clothing that could trap a stinging insect when outdoors.
After an outbreak of hives has gone away, avoid wearing tight-fitting clothing and stay away from hot baths or showers for a while. Both can cause the hives to return.
If the hives persist, get a thorough medical evaluation. There are some rare immune disorders that can cause hives, but only a comprehensive exam can determine that. If you have hives that linger for six weeks or more, ask your primary care doctor for advice. He or she may refer you to a specialist such as an allergist or immunologist. They can do skin or blood tests to help determine what foods or other substances trigger your hives.
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