First Aid for Spider bites

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Spider bites

Not all spiders affect the human health; however, there are some such as the black widow spider and the brown recluse that are medically significant spiders because their bites are detrimental to humans. Spider bites are often not detected until the signs and symptoms begin to appear.

However, symptoms may be caused by other factors such as chemicals, infections or allergies that are mistaken to be spider bites. If you suspect that you have been bitten by a spider, look for one in your household and try to identify it through markings, color etc., so that you can tell your doctor about what caused the symptoms.

The black widow spider and the brown recluse prefer dark and warm climates where there are ample flies to hunt on. You will find them in dry, dirty, peaceful areas where there is no human interruption, such as closets, under sinks and wood piles.


Almost every spider is venomous; however, severe effects are very rare because the venom is either weak or discharged in small amounts. Symptoms of a spider bite are similar to insect bites:

black widow
A Black Widow, pictured above, can produce a bite that can be fatal to humans.
  • Pain
  • Redness
  • Itching
  • Swelling


  1. Black widow spider

A black widow spider is identified with a red marking, shaped like an hour glass on its abdomen. Black widow spider bites often lead to severe cases but are only occasionally deadly. The bite will feel like a mere pinprick and you will not be able to feel the bite. The bite will only be identified once the signs and symptoms such as light red marks and swelling appear. After a few hours, you will experience the following symptoms:

  • Severe pain
  • Faint red marks
  • Chills
  • Fever
  • Abdominal pain
  • Nausea and vomiting

Brown recluse spider

The spider may have a violin shaped marking on its back which is sometimes inconsistent. Effects of a bite will start with a mild stinging sensation after which, redness and severe pain will occur. The remaining symptoms are as follows:

  • Fluid filled blister forms that eventually leave a deep and expanding ulcer
  • Mild fever
  • Nausea and vomiting
  • Rapid pulse
  • Muscle cramps
  • Sweating
  • Fatigue
  • Usually in children, death may also result


  1. Try to identify the type of spider that bit you. If you the spider is nearby, remember its markings, color, pattern, size etc.
  2. Clean the affected region thoroughly with soap and water.
  3. Apply a cool compress on the affected region.
  4. If practical, elevate the region to encourage blood flow.
  5. For adults, over-the-counter pain relievers such as aspirin and acetaminophen can be used to relieve pain. Antihistamines can also be used to alleviate symptoms of the spider bite. Do NOT give aspirin to children and teenagers suffering from flu-like symptoms, chicken pox or viral infections. Consult your doctor for further guidance.

In case of a black widow spider or brown recluse bite, follow these steps:

  1. Use soap and water to thoroughly cleanse the affected region.
  2. Try to stop or slow down the venom from radiating to other regions of your body. If the spider has bitten any one of your limbs, tie a bandage above the affected region and elevate it to slow down movement of the venom. Make sure that you do not tie the bandage too tight as it may interfere with your natural blood circulation.
  3. Apply a cold cloth (cloth soaked in cold water) on the affected region.
  4. Seek emergency medical treatment to receive anti-venom medication.

Doctors suggest getting tetanus shots every 10 years to make you less susceptible to infections. If you have received a tetanus shot within the last 5 years, get a booster shot in case, you have been bitten by a spider or any other insect that may lead to serious infection.

Learn More About Poisonings

To learn more about poisonings and other types of bites, including spider bites, enrol into St Mark James training programs. We are partnered with the leading providers in the Country. Training partners are located in Calgary, Edmonton, Winnipeg, Vancouver, Toronto, Ottawa, Halifax, and many more.

Related Video on Spider Bites

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