This poisoning is from a bite by a black widow spider (Latrodectus mactans).

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

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

This first symptom is usually pain similiar 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:

• Muscle weakness
• Numbness  
• Increased sweating
• Increased salivation
• Difficulty breathing
• Nausea and vomiting
• Restlessness
• Anxiety
• Headache
• High blood pressure

Pregnant women may have contractions and go into premature labor.

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

Determine the following information:

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

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 U.S. use this national number.

The symptoms may be treated with a variety of therapies, including:

• Pain medication
• Muscle relaxants
• Blood pressure drugs

In severe cases, anti-venin medication will be given. This drug may cause a dangerous reaction in people who are allergic to horses.

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.  

Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002: 794-795.

Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001:829-832.