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Brown recluse spider

The brown recluse spider's bite is poisonous. The scientific name for the brown recluse is Loxosceles reclusa.

This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the National Poison Control Center at 1-800-222-1222.

Alternative Names

Loxosceles reclusa

Poisonous Ingredient

Brown recluse spider venom

Where Found

The brown recluse spider is most common in the south and central states of the United States, especially in Missouri, Kansas, Arkansas, Louisiana, eastern Texas, and Oklahoma. However, the spider has been found in several large cities outside this range.

The brown recluse spider prefers dark, sheltered areas such as under porches and in woodpiles.

Symptoms

When the spider bites you, you may feel a sharp sting or nothing at all. Pain usually develops within the first several hours after being bitten, and may become severe. Children may have more serious reactions.

Symptoms may include:

  • Chills
  • Itching
  • General ill-feeling or discomfort
  • Fever
  • Nausea
  • Reddish or purplish color in a circle around bite
  • Sweating
  • Ulcer in the area of the bite

In rare cases:

  • Coma
  • Blood in urine
  • Jaundice
  • Kidney failure
  • Seizures

Home Treatment

Seek immediate emergency medical treatment and call 911 or the local emergency aid number, or poison control. Wash the area with soap and water. 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. Reduce ice contact time for individuals who have circulatory problems.

Before Calling Emergency

Before calling emergency, determine the following:

  • Patient's age, weight, and condition
  • The body part affected
  • The time the bite occurred
  • The type of spider

The patient should be taken to the emergency room for treatment. The bite may not appear to be serious, but it can take some time to become severe. Treatment is important to reduce complications. If possible, place the spider in a secure container and bring it to the emergency room for identification.

Poison Control

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, including insect bites. 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 will be treated as appropriate. Because brown recluse spider bites can be painful, pain medicines may be given. Antibiotics may also be prescribed if the wound is infected.

If the wound is near a joint (such as a knee or elbow), the arm or leg may be placed into a brace or sling. If possible, the arm or leg will be elevated.

In more serious reactions the patient may receive:

  • Blood and urine tests
  • Breathing support, if needed
  • Chest x-ray
  • EKG (electrocardiogram, or heart tracing)
  • Fluids through a vein (by IV)

The brown recluse spider bite can leave a large crater and ugly scarring. It is possible that surgery may be needed weeks later to improve the appearance of the scar.

Outlook (Prognosis)

Deaths from brown recluse spider bites are more common in children. With proper medical attention, survival past 48 hours is usually a sign that recovery will follow. An ulcer may take up to 6 weeks to heal, with proper care.

Wear protective clothing whenever possible when traveling through terrain which is known to harbor these spiders. Do not stick your hands or feet in their nests or in their preferred habitats, namely, under logs or underbrush, or other damp, moist areas.

References

Peterson ME. Brown spider envenomation. Clin Tech Small Anim Practice. 2006;21(4):191-193.

Boyer LV, Greta J. Binford GJ, Degan JA. Spider Bites. In: Auerbach PS, ed. Wilderness Medicine. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2011:chap 52.

Updated: 10/20/2013

Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.


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