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Symptoms
By Mayo Clinic staffTypically, a spider bite looks like any other bug bite — a red, inflamed, sometimes itchy or painful bump on your skin — and may even go unnoticed. Harmless spider bites usually don't produce other symptoms.
Black widow spider bites
Signs and symptoms of a black widow spider bite may include:
- Pain. Typically beginning within an hour of being bitten, pain can spread from the bite site into your abdomen, back or chest.
- Cramping. Abdominal cramping or rigidity can be so severe that it's sometimes mistaken for appendicitis or a ruptured appendix.
- Sweating. Excessive sweating can occur around the bite mark or may involve the entire limb.
Brown recluse spider bite
The pain associated with a brown recluse spider bite typically increases during the first eight hours after the bite. The bite usually heals on its own in about a week. In a minority of cases, the skin at the center of the bite can become dusky red and then evolve into a deep open sore (ulcer) that enlarges as the surrounding skin dies. The ulcer usually stops growing within 10 days after the bite, but full healing can take months.
When to see a doctor
Seek prompt medical assistance if you believe you've been bitten by a spider and you're experiencing:
- Severe pain
- Abdominal cramping
- A growing ulcer at the bite site
- Vetter RS, et al. Approach to the patient with a suspected spider bite: An overview. http://www.uptodate.com/home. Accessed March 12, 2013.
- Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh, U.K.; New York, N.Y.: Mosby Elsevier; 2010. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-0-7234-3541-9..X0001-6--TOP&isbn=978-0-7234-3541-9&uniqId=230100505-57. Accessed March 12, 2013.
- Spider bites. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/injuries_poisoning/bites_and_stings/spider_bites.html?qt=spider bites&alt=sh. Accessed March 14, 2013.
- Kliegman RM, et al. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa.: Saunders Elsevier; 2011. http://www.mdconsult.com/das/book/body/208746819-6/0/1608/0.html. Accessed March 12, 2013.
- Venomous spiders. National Institute for Occupational Safety and Health. http://www.cdc.gov/niosh/topics/spiders. Accessed March 12, 2013.
- Vetter RS, et al. Bites of widow spiders. http://www.uptodate.com/home. Accessed March 12, 2013.
- Vetter RS, et al. Bites of recluse spiders. http://www.uptodate.com/home. Accessed March 12, 2013.
- Brown recluse spider. Occupational Safety and Health Administration. http://www.osha.gov/OshDoc/data_Hurricane_Facts/brown_recluse_spider.pdf. Accessed March 15, 2013.
- Auerbach PS, et al. Wilderness Medicine. 6th ed. Philadelphia, Pa.: Mosby Elsevier; 2012. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B978-1-4377-1678-8..00052-0&isbn=978-1-4377-1678-8&sid=1418655681&uniqId=405544036-3#4-u1.0-B978-1-4377-1678-8..00052-0. Accessed March 15, 2013.
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