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Healthy Children > Tips & Tools > KidsDoc Symptom Checker > symptomviewer
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Spider Bite

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Definition

  • Bite from a spider

Symptoms of a Spider Bite

  • Most spider bites cause local pain, redness and swelling. It's much like a bee sting reaction.
  • A few spiders (such as the Black Widow) can cause a more severe reaction.
  • Helpful if spider seen on the skin or around the child

Cause of Spider Bite Reactions

  • Most spiders have tiny fangs. They inject venom into the skin.
  • The venom is what causes all the symptoms.

Types of Spider Bites

Black Widow Spider Bite

  • A shiny, jet-black spider with long legs (total size 1 inch or 25 mm).
  • A red (or orange) hourglass-shaped marking on its under-side.
  • Causes immediate local pain and swelling.
  • Sometimes, you can see 2 fang marks at the bite site.
  • Severe muscle cramps (especially stomach cramps) occur within 1 to 6 hours. These last 24 to 48 hours.
  • Rarely causes death. Exception: bitten by several spiders or small child is bitten.
  • Note: many are dry bites because the fangs are small.
  • The brown widow spider is related to the black widow. It is found in southern US.
  • Brown widow spider bites are treated the same as black widow bites.

Brown Recluse Spider Bite

  • A brown spider with long legs (total size ½ inch or 12 mm).
  • A dark violin shaped marking on top of its head.
  • Causes pain at the bite. Blisters form within 4 to 8 hours.
  • The center becomes bluish and depressed (crater-like) over 2 to 3 days.
  • Skin damage may require skin grafting in 10% of cases.
  • Other symptoms such as fever, vomiting, muscle pain can occur. No life-threatening symptoms occur.
  • Brown recluse spiders are hard to identify. If you can, bring the spider along in a jar.

Non-dangerous Spider Bites

  • More than 50 spiders in the U.S. have venom. Their bites cause reactions that are not serious. This includes pain or redness at the bite site.
  • The bites are painful and swollen. This lasts for 1 or 2 days. They can feel and look like a bee sting.
  • Some single, unexplained, tender bites that occur during the night are due to spiders.
Barton Schmitt MD, FAAP
Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.
Copyright 2000-2025 Schmitt Pediatric Guidelines LLC.
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