Hives

What are hives?

Hives are a very itchy rash caused by an allergic reaction. Hives look like raised pink spots with pale centers on the skin. The spots range from 1/2 inch to several inches wide (hives often look like mosquito bites). The spots may be different shapes. The spots rapidly and repeatedly change in location, size, and shape.

What is the cause?

Widespread hives are an allergic reaction to a food, medicine, viral infection, insect bite, and a host of other substances. Often the cause is not found. Hives found on just one part of the body (localized) are usually due to skin contact with plants, pollen, food, or pet saliva. Localized hives are not caused by drugs, infections, or swallowed foods. Hives are not contagious.

How long do they last?

More than 10% of people get hives. Most teens who develop hives have it only once. The hives come and go for 3 or 4 days and then mysteriously disappear.

How can I take care of myself?

• Antihistamine medicine

  The best drug for hives is an antihistamine. An antihistamine won't cure the hives, but it will reduce their number and relieve itching.

  Benadryl, one of the most commonly used drugs for hives, has recently become available without prescription. The main side effect of this drug is drowsiness. If you have another antihistamine (for example, any drug for hay fever) at home, use it until you can get some Benadryl. If you are taking Benadryl, take it 4 times a day in the following doses:

   
                                Your weight (pounds) 
                           80        100    120 or more 
      ----------------------------------------------------
      Benadryl liquid     13 ml     16 ml     20 ml 
      Benadryl tablets      1       1+1/2       2 
      ----------------------------------------------------
      Notes:  Concentration of liquid:  12.5 mg/5 ml 
              Tablets are 25-mg tablets 
  

  Your drug is _____________________________. Take ___________ every ______ hours. Continue the medicine until the hives are completely gone for 24 hours.

• Itching

  Take a cool bath to relieve itching. Put a cold washcloth or ice cube on itchy areas for 10 minutes. Avoid heat or rubbing.

• Avoidance and showers

  Avoid anything you think might have caused the hives. For hives triggered by pollen or animal contact, take a cool shower or bath. For localized hives, wash the allergic substance off the skin with soap and water. Localized hives usually disappear in a few hours and don't need Benadryl.

• Common mistakes in the treatment of hives

  Many people wait to take the antihistamine until new hives have appeared. This means you will become itchy again. The purpose of the medicine is to keep you comfortable until the hives go away. Therefore, take the medicine regularly until you are sure the hives are completely gone.

  Since hives are not contagious you can be with other people.

When should I call my health care provider?

Call IMMEDIATELY if:

• Breathing or swallowing becomes difficult.
• You start feeling very sick.

Call during office hours if:

• Most of the itch is not relieved after you have been taking an antihistamine for 24 hours.
• The hives last more than 1 week.
• You have other concerns or questions.