Health Encyclopedia

Black widow spider

Definition

The black widow spider (Latrodectus mactans) has a shiny black body with a red hourglass-shape on the belly area. The bite of a black widow spider is poisonous.

Poisonous Ingredient

The venom of the black widow spider contains poisonous chemicals that make people sick.

Where Found

Black widows are found throughout the United States but predominantly in the South and West. They are usually found in barns, sheds, stone walls, fences, woodpiles, porch furniture, and other outdoor structures.

Symptoms

This first symptom is usually pain similar to a pinprick. This sensation is felt when the bite is actually made. Some people may not feel it. There may be minor swelling and redness.

Fifteen minutes to an hour later, a dull muscle pain spreads from the bite area to the entire body.

If the bite is on the upper body, you will usually feel most of the pain in your chest.
If the bite is on your lower body, you will usually feel most of the pain in the abdomen.

The following symptoms can also occur:

Anxiety
Difficulty breathing
Extremely painful muscle cramps
Headache
High blood pressure
Increased salivation
Increased sweating
Muscle weakness
Nausea and vomiting
Numbness
Restlessness

Pregnant women may have contractions and go into premature labor.

Home Treatment

Seek immediate emergency medical treatment. Wrap ice in a washcloth or similar material and place it on the bite area. Leave it on for 10 minutes and then off for 10 minutes. Repeat this process.

Before Calling Emergency

Determine the following information:

Patient's age, weight, and condition
Time the bite occurred
Area where the bite occurred
Type of spider, if possible

Poison Control, or a local emergency number

The National Poison Control Center (1-800-222-1222) can be called from anywhere in the United States. This national hotline number will let you talk to experts in poisoning. They will give you further instructions.

This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.

See: Poison control center - emergency number

What to expect at the emergency room

The health care provider will measure and monitor the patient's vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms may be treated with a variety of therapies, including:

Blood pressure drugs
Muscle relaxers
Pain medicines

In severe cases, anti-venin medication to reverse the effect of the poison will be given. However, this drug can cause serious allergic reactions.

Expectations (prognosis)

Severe symptoms usually go away within 2 to 3 days, but milder symptoms may persist for several weeks. Death in a normally healthy individual is very rare. Young children may not survive a bite.

References

Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001.

Ford MD. Clinical Toxicology. 1st ed. Philadelphia, Pa: WB Saunders; 2001.

Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002.

Review Date:10/29/2007
Reviewed By:Eric Perez, MD, Department of Emergency Medicine, St. Luke's-Roosevelt Hospital Center, New York, NY. Review provided by VeriMed Healthcare Network.

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