SPIDER BITE
Definition
- Bite from a spider seen on the skin.
- Onset of bite symptoms (redness, pain, swelling) and a spider is seen in close proximity
General Information
- There are over 20,000 species of spiders in the world.
- In the United States, there are two species that cause bites in humans of medical importance: the black widow (Lactrodectus) and the brown recluse (Loxosceles).
- If you decide you need to see your doctor, bring the spider along in a jar for identification (brown recluse spiders are especially hard to identify).
Black Widow Spider Bite
- 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 (not present in all Lactrodectus species).
- Black widow spiders are found throughout North America, except in Alaska and the far North.
- Causes immediate local mild pain, swelling, and occasionally 2 fang marks. Severe muscle cramps are present by 1 to 6 hours, and 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.
- First Aid for Black Widow Spider Bites: Apply an ice cube or ice pack to the bite for 20 minutes to reduce the spread of the venom (no tourniquet).
Brown Recluse Spider Bite
- Also known as the "violin" or "fiddleback" spider
- Is a brown spider with long legs (total width 1/2 inch). There is a dark violin-shaped marking on top of its head (not present in all Loxosceles species).
- It can be found in the southern, southwestern, and midwestern United States.
- Causes local pain and delayed blister formation in 4 to 8 hours. The center of the bite becomes bluish and depressed (crater-like) over 2 to 3 days. A deep necrotic ulcer may develop. Skin damage may require skin grafting in 10% of cases
- Generalized symptoms such as fever, vomiting, and muscle aches can occur (but no life-threatening symptoms).
Non-Dangerous Spider Bites
- More than 50 spiders in the U.S. have venom and can cause local, non-serious reactions.
- The bites are painful and mildly swollen for 1 or 2 days (much like a bee sting).
- Most single, unexplained, tender bites that occur during the night are due to spiders.
See More Appropriate Topic (instead of this one) If
- TICK BITES
- BEE STING
- Bite and not from a tick or spider, see INSECT BITES
WHEN TO CALL YOUR DOCTOR FOR SPIDER BITE
Call 911 Now (you may need an ambulance) If
- Difficulty breathing or swallowing
- Very weak (can't stand)
Call Your Doctor Now (night or day) If
-
You feel weak or very sick
- Any black widow spider bite
- Abdominal pain, chest tightness or other muscle cramps
- Vomiting
- Urine is brown, black or red in color
- Bite pain is severe
- Bite looks infected (red streaking from the bite area, yellow drainage) (Note: infection doesn't start until at least 24-48 hours after the bite. Any redness in the first 24 hours is due to venom)
Call Your Doctor Within 24 Hours (between 9am and 4pm) If
- You think you need to be seen
- Diabetic and spider bite of foot
- Bite starts to look bad (e.g. skin damage, blister or purplish - not just swelling)
- Bite pain persists longer than 2 days
Call Your Doctor During Weekday Office Hours If
- You have other questions or concerns
Self Care at Home If
- Non-serious spider bite and you don't think you need to be seen
HOME CARE ADVICE FOR NON-SERIOUS SPIDER BITE
- Cleansing: Wash the bite thoroughly with soap and water.
- Meat Tenderizer: Rub the bite area with a cotton ball soaked in a meat tenderizer solution for 20 minutes. (Exception: don't use near the eye.) If not available, apply an ice cube for 20 minutes.
-
Pain Medication: For pain relief, take acetaminophen every 4-6 hours
(e.g. Tylenol; adult dosage 650 mg) OR ibuprofen every 6-8 hours (e.g. Advil,
Motrin; adult dosage 400 mg).
- Do not take ibuprofen if you have stomach problems, kidney disease, are pregnant, or have been told by your doctor to avoid this type of anti-inflammatory drug. Do not take ibuprofen for more than 7 days without consulting your doctor.
- Do not take acetaminophen if you have liver disease.
- Read the package instructions thoroughly on all medications that you take.
- Expected Course: Some swelling and pain for 1 to 2 days. It shouldn't be any worse than a bee sting.
- Call Your Doctor If:
- Severe bite pain persists longer than 2 hours after pain medicine
- Abdominal pains or muscle spasms occur
- Local pain lasts more than 2 days (48 hours)
- Bite begins to look infected
- You become worse or develop any of the "Call Your Doctor" symptoms.
Disclaimer: This information is not intended be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information.
Adult SelfCareNavigator. Copyright © 2000-2005 David Thompson, M.D. FACEP
Reviewed 10/2005
Revised 7/2002
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