Most spider bites cause only minor injury. A few spiders can be dangerous. In the United States, these include the black widow spider and the brown recluse spider.
Seek emergency care immediately if:
- You were bitten by a black widow or brown recluse spider
- You are unsure whether the bite was from a poisonous spider
- You have severe pain, abdominal cramping or a growing ulcer at the bite site
- The person who was bitten isn't breathing
To take care of a spider bite:
- Clean the wound. Use mild soap and water and apply an antibiotic ointment.
- Apply a cool compress. Use a cloth dampened with cold water or filled with ice. This helps reduce pain and swelling. If the bite is on an arm or leg, elevate it.
- Take an over-the-counter pain medication if needed. If the wound is itchy, an antihistamine (Benadryl, Chlor-Trimeton, others) may help.
Your doctor may recommend a tetanus booster shot if you haven't had one in the last five years.
Black widow spider
You can usually identify a black widow spider by the hourglass marking on its belly. In the United States, this spider is more common in the South.
Signs and symptoms of a black widow spider bite may include:
- At first, slight swelling and faint red marks
- Intense pain and stiffness
- Severe abdominal pain or cramping
- Chills, fever and nausea
Brown recluse spider
The brown recluse spider has a violin-shaped marking on its back, but this mark can be hard to see. In the United States, its range is central and southern states.
Signs and symptoms of a brown recluse spider bite vary but may include:
- At first, a mild pain
- Redness and intense pain
- A deep blue or purple area around the bite, which may develop a red ring around it
Show References
- What to do in a medical emergency: Bites and stings. American College of Emergency Physicians Foundation. http://www.emergencycareforyou.org/Emergency-101/Emergencies-A-Z/Bites-and-Stings/. Accessed Dec. 13, 2017.
- Kasper DL, et al., eds. Bites, venoms, stings, and marine poisonings. In: Harrison's Manual of Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2016. http://accessmedicine.mhmedical.com. Accessed Dec. 13, 2017.
- Kermott CA, et al., eds. Conditions A-Z. In: Mayo Clinic Book of Home Remedies. 2nd ed. New York, N.Y.: Time Inc. Books; 2017.
- Juckett G. Arthropod bites. American Family Physician. 2013;88:841.
- Spider bites. Merck Manual Professional Version. https://www.merckmanuals.com/professional/injuries-poisoning/bites-and-stings/spider-bites. Accessed Dec. 13, 2017.
- Knoop KJ, et al., eds. Environmental conditions. In: The Atlas of Emergency Medicine. 4th ed. New York, N.Y.: McGraw-Hill Education; 2016. http://www.accessmedicine.mhmedical.com. Accessed Dec. 13, 2017.
Original article: https://www.mayoclinic.org/first-aid/first-aid-spider-bites/basics/ART-20056618