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Black Widow Spider
Brown Recluse Spider
- Bite from a spider seen on the skin
- Onset of bite symptoms (redness, pain, swelling) and a spider is seen in close proximity
- 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).
- Sometimes people incorrectly believe that they sustained a spider bite, when instead a minor break in the skin instead simply became infected with a bacteria called Staphylococcus aureus.
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.
If not, see these topics
|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
- 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 9 am and 4 pm) 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
And remember, contact your doctor if you develop any of the "Call Your Doctor" symptoms.
- 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). Do this just once.
- If not available, apply an ice cube for 20 minutes.
- Pain Medication:
- For pain relief, take acetaminophen or ibuprofen.
- Acetaminophen (e.g., Tylenol): The dose is 650 mg by mouth every 4 hours or 1000 mg by mouth every 6 hours. Maximum dose per day = 4000 mg.
- Ibuprofen (e.g., Motrin, Advil): The dose is 400 mg by mouth every 6 hours or 600 mg by mouth every 8 hours.
- People who are over 65 Years of age: Acetaminophen is generally considered safer than ibuprofen. Acetaminophen dosing interval should be increased to every 8 hours because of reduced liver metabolism. Maximum dose per day = 3000 mg.
- CAUTION: 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.
- CAUTION: 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
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.
Author and Senior Reviewer: David A. Thompson, M.D.
Last Reviewed: 1/19/2009
Last Revised: 4/5/2008
Content Set: Adult HouseCalls Online
Portions Copyright 2000-2009 Self Care Decisions LLC; Copyright LMS, Inc.