Spider bite definition and facts

  • Most spiders in the US are harmless. However, black widow and brown recluse spider bites are dangerous, and sometimes life threatening. Black widow and brown recluse spider bites need immediate medical treatment.
  • Spider bites are actually rare occurrences, and most presumed cases of spider bites are likely due to another condition that mimics the symptoms or signs of a spider bite.
  • Bites from most (non-poisonous) spiders cause local redness, irritation, and pain that usually can be treated at home.
  • Black widow spider bite symptoms are:
    • Immediate pain
    • Burning
    • Redness
    • Swelling
  • Other signs and symptoms of a black widow spider bite are a feeling of a pinprick, and sometimes double fang marks on the person where the spider bit. Often, a person does not know that a black widow spider has bitten them.
  • Symptoms of a brown recluse spider bite are a mild sting followed by severe pain and local redness that usually develops within eight hours or more after the bite. Some brown recluse spider bites may include a purple or blue area around the bite, which is surrounded by a whitish ring and a large outer ring in a bull’s eye pattern. A fluid blister then forms at the spider bite site, and then sloughs off revealing a deep ulcer that may turn black.
  • Other signs and symptoms of a black widow or  brown recluse spider bite may include:
  • If you think that, you or someone you know has been bitten by a black widow or brown recluse spider, go to the nearest Urgent Care or Emergency Department for treatment.

What are the symptoms of a non-poisonous spider bite?

Bites from most (non-poisonous) spiders cause local redness, irritation, and pain that usually can be treated at home using an over-the-counter pain reliever along with application of cooling packs or a wet cloth to relieve swelling. These local reactions usually resolve without treatment over a period of 7-10 days. Rarely, an individual can have an allergic reaction to a spider bite, even to a bite from a non-poisonous spider, but allergic reactions are more likely to be due to contact with a spider than from a spider bite.

Spider Bites: Black Widow vs. Brown Recluse First Aid

Spider Bites

Spider Bite Remedies

What should you do if you are bitten by a spider?

  • Wash the site of the spider bite well with soap and water.
  • Apply a cool compress or ice pack over the spider bite location.
  • Over-the-counter pain relievers may be used to relieve symptoms. (Remember, do not give aspirin to children; use acetaminophen or ibuprofen instead).
  • Call the doctor or seek emergency treatment if the victim is a young child, if you think the bite may have been from a black widow or brown recluse spider, if any signs of an allergic reaction occur, if the bite area becomes infected, or if the victim develops a rash or severe illness.
  • If possible, retrieve the spider and bring it with you to the health care practitioner so that it can be definitively identified.
  • A tetanus booster shot may be necessary, depending upon the date of the patient’s last immunization.

What are the signs and symptoms of a black widow spider bite? What does the spider look like (pictures)?

A black widow spider bite is said to feel like a pinprick, although victims may not realize that they have been bitten. Sometimes double fang marks may be seen at the location of the bite. The most common localized symptoms of a black widow spider bite include:

  • Immediate pain
  • Burning
  • Swelling
  • Redness
Picture of the underside of a black widow spider and an egg sack

Picture of the underside of a black widow spider and an egg sack

Picture of a top view of a black widow spider

Picture of a top view of a black widow spider

What are the symptoms of a brown recluse spider bite? What does the spider look like (pictures)?

The bite of a brown recluse spider leads to a mild stinging, followed by local redness and severe pain that usually develops within eight hours but may occur later. Some reports of brown recluse bites describe a blue or purple area around the bite, surrounded by a whitish ring and large red outer ring in a “bull’s eye” pattern. A fluid-filled blister forms at the site and then sloughs off to reveal a deep ulcer that may turn black.

Picture of a brown recluse spider. Note the violin pattern on the cephalothorax and light-colored hairless abdomen.

Picture of a brown recluse spider. Note the violin pattern on the cephalothorax and light-colored hairless abdomen.

Picture of a brown recluse spider

Picture of a brown recluse spider

Picture of a brown recluse spider head close-up

Picture of a brown recluse spider head close-up

Can black widow or brown recluse spider bite symptoms be the same?

Generalized symptoms of bites from black widow and brown recluse spiders may include:

Rarely, black widow spider bites are fatal; however, a few individuals have died from brown recluse spider bites, which are more common in children than in adults.

If a spider was not observed inflicting the bite, it is difficult if not impossible to determine whether a spider bite occurred, since many conditions of the skin may produce the same symptoms as a spider bite. Streptococcal and Staphylococcal infections, early lesions of herpes simplex or zoster, burns, stings or bites from other arthropods or insects (including fleas, bedbugs, mosquitos, biting flies, ants, and ticks), thorn injury, and early Lyme disease all may be characterized by skin findings similar to those from a spider bite.

Spiders rarely bite people, and only if threatened. People often thing they have spider bites when the irritation is from another cause.

Are spider bites dangerous?

Most spiders do not have mouth parts strong enough to penetrate human skin, and the majority of spiders found in the U.S. and are actually harmless. There are two notable exceptions, the black widow spider and the brown recluse spider, which are both dangerous to humans. Spider bites are fortunately uncommon. In many cases, presumed spider bites are actually due to another skin condition or an insect sting.

The black widow and brown recluse spiders are more common in the southern states of the U.S. They prefer warm, dry climates and undisturbed areas such as basements, closets, woodpiles, attics, or under sinks. The black widow spider is a small, black, shiny spider with a red hourglass marking on its belly. The brown recluse spider is sometimes termed a “violin spider.” It is about an inch long and has a marking resembling a violin on the upper part of its back. Bites from both the black widow and brown recluse spiders are dangerous to humans and require prompt emergency medical care.

What should you do if a spider bites you?

  • Wash the site of the spider bite well with soap and water.
  • Apply a cool compress or ice pack over the spider bite location.
  • Over-the-counter pain relievers may be used to relieve symptoms. (Remember, not to give aspirin to children; use acetaminophen or ibuprofen instead).
  • Call the doctor or seek emergency treatment if the victim is a young child, if you think the bite may have been from a black widow or brown recluse spider, if any signs of an allergic reaction occur, if the bite area becomes infected, or if the victim develops a rash or severe illness.
  • If possible, retrieve the spider and bring it with you to the health care practitioner so that it can be definitively identified.
  • A tetanus booster shot may be necessary, depending upon the date of the patient’s last immunization.

What should you do if a black widow or brown recluse spider bites you?

  • Wash the bite area with soap and water.
  • Elevate the area to prevent spread of the venom.
  • Tie a snug bandage above the area (if on an arm or leg) to further reduce spread of the venom, but do not make the bandage too tight that it impairs the blood circulation.
  • Always seek immediate emergency medical care. An anti-venom medication is sometimes given for black widow spider bites. Doctors’ use different types of medications to treat spider bites, including pain relievers, muscle relaxants, and/or corticosteroids. Sometimes hospitalization is required after black widow or brown recluse spider bites.
  • If possible, retrieve the spider and bring it with you to the health care practitioner so that it can be definitively identified.
  • A tetanus booster shot may be necessary, depending upon the date of the patient’s last immunization.
  • Calling the Poison Control Center (24-hour hotline at 1-800-222-1222 in the U.S.) allows you to reach toxicology experts who can work with a health care provider in establishing the proper diagnosis and management of a spider bite.

Medically Reviewed on 4/23/2018

References

REFERENCE: Burns, (Bo)D, DO, FACEP, FAAEM. Insect Bites. Medscape. Updated: May 16, 2017.
<https://emedicine.medscape.com/article/769067-overview>