Treating Spider Bites

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Treating Spider Bites

Question:

What is the proper treatment for a spider bite?

Answer:

Some spider bites cause only limited discomfort and can be treated at home with an ice pack and oral antihistamine to reduce swelling, and a topical antibiotic.

Other spider bites cause large swellings and slow-to-heal ulcers at the site of the bite. They may require oral antibiotics and other prescription medications.

Still other spider bites can cause severe damage to blood vessels, kidneys, red blood cells, and other parts of the body as well as swelling and necrosis (tissue death) at the site of the bite. Emergency room treatment and hospitalization may be necessary in severe cases.

Whether a severe or a limited reaction occurs to a spider bite depends on the species of spider and the health and age of the person bitten. Children and the elderly are affected most severely.

Among the species in the United States that can cause severe reactions are the black widow spider and the brown recluse spider. Black widow spiders are usually black with a red hourglass or a row of red dots on their abdomens. They inject neurotoxic venom with their bite, which can result in severe abdominal pain, difficulty breathing, nausea, vomiting, fever, sweating, and increased blood pressure.

Brown recluse spiders are usually yellow-brown with a violin pattern on the back. Their bite can cause pain and swelling at the bite site, which can grow into a large ulcer with necrotic (dead) skin that is very slow to heal. In some severe cases, kidney failure or other problems can occur.

If you have been bitten by a spider and have symptoms other than mild stinging at the site of the bite, go to the emergency room immediately. If possible to do safely, take the spider with you in a closed container (glass jar with a top) so that it may be identified. Antivenom is sometimes available for bites by the black widow or brown recluse spiders.

Rebecca Campen, M.D., J.D. is an Assistant Professor of Dermatology at Harvard Medical School. She divides her time between clinical practice of dermatology at the Massachusetts General Hospital and private practice in Savannah, Ga.

Last updated:	July 20, 2009