What are hives?
Hives are a very itchy rash usually 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. Giant hives are called angioedema. This can cause large swelling beneath the skin, especially of the face.
What is the cause?
Widespread hives usually are a reaction to a viral infection. Less commonly they are an allergic reaction to a food, medicine or bee sting. Often the cause is not found (more than 30%). Hives 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 an allergy and not caused by drugs, infections, or swallowed foods. Hives are not contagious.
Rarely, hives may also be caused by:
- Exposure to cold air or water
- Exposure to sunlight
- Becoming overheated from exercise or a hot shower
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 4Â 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 (diphenhydramine), is the most commonly used drug for hives, and is available without a prescription. The main side effect of this drug is drowsiness in some people. Other antihistamines (for example, store brands of any drug for hay fever) will also help. If you are taking Benadryl, take it 3 to 4 times a day until the hives are gone for 12 hours.
Use the drug recommended by your healthcare provider.
For flare-ups of itching, take a cool bath without soap for 10 minutes. 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. Avoid heat or rubbing, which makes hives worse.
- 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 healthcare provider?
Call IMMEDIATELY if:
- Breathing or swallowing becomes difficult.
- You start feeling very sick.
Call during office hours if:
- The hives last more than 1 week.
- You have other concerns or questions.
Written by Barton D. Schmitt, MD, author of â€œMy Child Is Sick,â€ American Academy of Pediatrics Books.
Pediatric Advisor 2015.1 published by RelayHealth.
Last modified: 2012-09-25
Last reviewed: 2014-06-10
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright Â©1986-2015 Barton D. Schmitt, MD. All rights reserved.