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Spider Bite


  • 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.

When To Call

Call 911 Now

  • Trouble breathing or wheezing
  • Passed out (fainted) or too weak to stand
  • You think your child has a life-threatening emergency

Go to ER Now

  • Black or brown widow spider bite suspected
  • Stomach pain, chest tightness or other muscle cramps
  • Bite pain is severe and not improved after using care advice

Call Doctor or Seek Care Now

  • Fever and bite looks infected (spreading redness)
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Contact Doctor Within 24 Hours

  • New redness starts more than 24 hours after the bite. Note: any redness in the first 24 hours is due to venom.
  • More than 48 hours since the bite and redness now getting larger
  • Bite starts to look bad (such as skin damage, blister or purple color)
  • Bite pain lasts more than 2 days
  • You think your child needs to be seen, but the problem is not urgent

Contact Doctor During Office Hours

  • You have other questions or concerns

Self Care at Home

  • Non-serious spider bite

Care Advice

What You Should Know About Spider Bites:

  • Most spider bites look and feel like a bee sting.
  • The main symptoms are pain and redness.
  • Here is some care advice that should help.

Clean the Bite:

  • Wash the bite well with soap and water.

Cold Pack for Pain:

  • For pain or swelling, use a cold pack. You can also use ice wrapped in a wet cloth.
  • Put it on the bite for 20 minutes.

Pain Medicine:

  • To help with the pain, give an acetaminophen product (such as Tylenol).
  • Another choice is an ibuprofen product (such as Advil).
  • Use as needed.

What to Expect:

  • The swelling and pain lasts for 1 to 2 days.
  • It should not be any worse than a bee sting.

Call Your Doctor If:

  • Severe bite pain lasts more than 2 hours after pain medicine
  • Stomach pains or muscle cramps occur
  • Bite pain lasts more than 2 days (48 hours)
  • Bite starts to look infected
  • You think your child needs to be seen
  • Your child becomes worse



Black widow spider

This is a photo of the Black Widow spider.

  • The black widow is shiny and black, with long legs (total width 1 inch).
  • A red or orange hourglass-shaped marking may be on its underside. However, this marking is not present in all black widow spiders.

Source: CDC PHIL
From the CDC's Public Health Image Library (, ID#5449, in the public domain.

Brown recluse spider

This is a photo of the Brown Recluse Spider.

  • It is a brown spider with long legs (total width 1/2 inch).
  • A violin-shaped marking can be seen on its back.

Source: CDC PHIL
From the CDC's Public Health Image Library (, ID#1125, in the public domain.

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.
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