Health Topics for Prepare for Emergencies

Department of Emergency Medicine

Emergency Medical Services Learning Resources Center

Bites: Spiders

Only a few spiders cause serious bites. Most spider bites are not serious and do not require medical evaluation.

Symptoms of a minor spider bite usually go away in 2 to 3 days. At first, the person may experience some local pain, redness, and swelling.

Self-care for a minor spider bite includes the following:

• clean the area with mild soap and water
• apply cold compresses to keep swelling down
• consider using an over-the-counter topical hydrocortisone cream to reduce the itching and
• take an over-the-counter pain reliever like aspirin or acetaminophen (Aspirin or medicines that have aspirin in them should not be given to anyone younger than 18 years of age. Taking aspirin is a risk for a serious illness called Reye's syndrome. Acetaminophen should not be taken by anyone with known liver or kidney disease. Do not drink alcohol when taking more than 1 dose of acetaminophen.)

Be sure to check with your healthcare provider to see if a tetanus booster shot is needed. This may be recommended if the skin is broken and infection develops. Avoid scratching the bite because this may prolong symptoms for several weeks.

There are three types of spiders and spider-related creatures found in the United States whose bites can be serious. These include:

• the black widow spider
• the brown recluse spider and
• one type of scorpion found in the southwestern United States

The black widow is a shiny, black spider with a fat body and a distinctive red or orange hourglass figure on its underside. It can be found throughout most of the country in woodpiles, sheds, and bowls of outdoor toilets.

The brown recluse spider is brown in color, has a violin mark on its head, and long brown legs. It is active mostly at night and can be found in cracks and crevices of houses in the southern and southwestern United States.

Scorpions are related to spiders and have a long body and tail that curls up when they are about to sting. Only one species of scorpion found in the United States is harmful to humans. This species is found in the southwestern United States.

Initial symptoms of poisonous spider bites or scorpion stings may include:

• pain
• swelling
• tiny red bite marks
• tenderness
• skin discoloration
• numbness and
• tingling

Symptoms usually worsen with time and, depending on the type of spider or scorpion, more serious symptoms may be noticed within 10 minutes to 8 hours of the bite or sting.

More serious spider bite symptoms may include:

• severe pain at the site of the bite
• muscle spasms
• abdominal pain or cramps
• dizziness
• convulsions
• wheezing or difficulty breathing
• fever
• chills
• general weakness
• nausea
• vomiting
• drowsiness
• difficulty talking and
• itching of the nose, throat, and mouth

If you know that you have been bitten or stung by a poisonous spider or scorpion, or if you are having any of these symptoms, immediately apply a small ice bag or cold compress to the bite and see your healthcare provider or go to your local emergency room.

To avoid getting bitten or stung by a poisonous spider or scorpion:

• spray areas that are infested with poisonous spiders or scorpions with an appropriate pesticide on a regular basis
• wear gloves and heavy clothing when around woodpiles or sheds
• inspect and shake outdoor clothing and shoes before putting them on
• inspect outdoor toilets carefully before using them
• discourage children from playing near spider and scorpion infested areas and
• raise entrances to homes by at least 8 inches to keep scorpions out

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIL File PREP4926.Rf2 VRS# 4926 Data Version 7.0 Copyright 1999-2000, 2003 McKesson Health Solutions LLC. All rights reserved.