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Black Widow Spider Bite

Black Widow Spider Bite Treatment continued...

Symptoms are often not easily relieved, even with narcotics. Some experts recommend that antivenin be used in any severe bite because 1 vial of the antitoxin produces significant and rapid relief of symptoms. It can even be used if there is delay in reaching the hospital. Yet other sources recommend that antivenin be used only in children, the elderly, and those with severe underlying medical conditions.

The obvious risk for using antivenin is allergic reaction to horse serum, and the bitten person must be skin-tested for this possibility. Although delayed serum sickness is common when horse serum is used to treat rattlesnake bites, it is uncommon when used to treat black widow spider bites (probably because of the low dose needed for relief).

Be aware, however, that this antivenin may not be readily available at most hospitals; there may be some delay or difficulty in obtaining it when needed.

Of interest: The use of the black widow antivenin might sensitize the person for later use of rattlesnake antivenin. Obviously, the physician should discuss lifestyle habits that might affect the person's risk of incurring a snakebite in the future. In many areas, black widow bites are much more common than rattlesnake bites.

Next Steps - Follow-up

In general, follow-up is only necessary in cases where antivenin is used. Although serum sickness is uncommon with single-vial doses of horse serum, it may occur 7-12 days after exposure and is characterized by skin lesions, fever, pain in the joints, and swollen lymph glands. The symptoms may occur sooner in a sensitized person. The process is self-limited, goes away in 2-3 weeks, and may be treated with antihistamines and steroids.


Because black widow spiders bite if they are disturbed, care should be taken in reaching into dark areas. This includes sitting down in an outhouse without first checking for other inhabitants. In areas where spider infestations are a problem, the use of a pest control service may also be useful.


Complications in healthy adults are uncommon. If the black widow spider bite is not treated with antivenin, symptoms may last for several days but are seldom life threatening.

WebMD Medical Reference from eMedicineHealth

Reviewed by Varnada Karriem-Norwood, MD on May 11, 2014
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