The brown recluse spider and the black widow spider are dangerous to humans because their fangs can penetrate skin and inject poisonous venom. Brown recluse spiders have an upside-down violin-shaped marking down their backs and live only in the Midwest. Black widow spiders are shiny with a distinctive red hourglass shape on the under-side of their abdomens.
Identification
If the victim did not see the spider, the appearance of the bite and the nature of the symptoms can help to identify it and guide subsequent treatment. According to the California Poison Control System, the center of a brown recluse bite develops into a blister, surrounded by a red ring, then a pale ring. In contrast, a bite from a black widow forms a ring of red surrounding a pale center.
Within about two hours of a serious black widow bite, the victim develops severe muscle cramps, weakness, nausea, sweating, headache, difficulty breathing and high blood pressure. In contrast, brown recluse bites cause burning and itching at the site within 10 minutes and an itchy red rash over the whole body later. More venom can cause fever and chills, vomiting, muscle aches and anemia.
Home Treatment
Often, venomous spider bites do not cause serious systemic symptoms and do not require any treatment beyond washing the area well with soap and water and applying an antibiotic ointment to prevent infection. To minimize the spread of venom, elevate and immobilize the site of the bite. Ice and pain medication can treat the site of the bite. According to the February 2005 issue of the journal "Medical Progress," most brown recluse bites heal on their own.
Hospital Treatment: Black Widow Bite
People who develop muscle cramps after a black widow bite should go to the hospital. Some hospitals stock black widow anti-venom, but it is reserved for the most serious cases because it can cause serious allergic reactions, according to the National Library of Medicine. Usually, blood pressure drugs, narcotics and muscle relaxants can treat the symptoms without resorting to anti-venom.
Hospital Treatment: Brown Recluse Bite
People who develop systemic symptoms after a brown recluse bite should seek medical attention. Doctors may administer pain medication, elevate the area of the bite and give antibiotics. The blister in the center of the brown recluse bite can break and form an ulcer. The California Poison Control System says the greatest risk from a brown recluse bite comes from an infected ulcer; occasionally, surgery is required to remove the dead or necrotic tissue.
Expert Insight
Although many people dread venomous spiders, the likelihood of a fatal spider bite is minuscule. Black widows do not always inject venom when they bite, and a venom-less bite will not cause any symptoms. Nobody in the United States has died from a black widow bite in more than 10 years, according to the California Poison Control System. Brown recluse bites seldom cause necrosis, and even serious cases are rarely life-threatening.
References
- California Poison Control: Spider Bites
- Survive Outdoors: Black Widow
- "Medical Progress"; David Swanson and Richard Vetter; "Bites of brown recluse spiders and suspected necrotic arachnidism"; February 2005
- National Library of Medicine: Black Widow Spider
- National Library of Medicine: Brown Recluse Spider
