Health A-Z

How serious is a spider bite?

Most spiders are harmless and rarely bite people. All spiders make venom (a poison), but most spiders’ fangs are too small to puncture human skin.

Spiders are arachnids (not insects). They’re in the same class as scorpions, mites and ticks. All of these arachnids have eight legs. Spiders perform a vital function by eating insects that can destroy crops.

What are the symptoms of a spider bite?

Spider bite symptoms vary depending on the type of spider.

Black widow spider bites cause an immediate, sharp, pinprick-like pain. The bite area then becomes numb. Other signs of a black widow spider bite include:

• Difficulty breathing.
• Droopy or swollen eyes.
• Headache.
• Increased saliva production.
• Nausea and vomiting.
• Painful muscle cramps and stiffness in the stomach, shoulders, chest and back.
• Profuse sweating.
• Itchy skin rash.

Bites from brown recluse spiders aren’t immediately painful or noticeable. Instead, you might feel pain an hour after the bite. Other signs of a brown recluse spider bite include:

• A blister surrounded by a bruise or reddish skin color (similar to a bull’s-eye). The blister may rupture and form a skin ulcer that later scars.
• Itchy skin in the bite area or all over the body.

Hobo spider bites rarely cause pain. Signs of a hobo spider bite include:

• Severe headache within minutes or hours after the bite. This headache may last for a week.
• Hardened skin in the bite area within 30 minutes of the bite.
• Red, swollen skin.
• Blisters that produce pus.
• Fatigue.
• Nausea.
• Cognitive impairment (memory problems).

What are the complications of a spider bite?

Some brown recluse bites cause a skin ulcer (wound). If the wound doesn’t heal, you might need surgery.

Black widow bites are the most serious. Children under 16 and people older than 60 may need hospitalization to treat:

• Breathing problems.
• Heart issues.
• High blood pressure.
• Severe muscle pain and cramping.

How is a spider bite managed or treated?

Spider bite treatments vary depending on symptoms. Treatment for black widow spider bites includes muscle relaxers, sedatives and pain medicines.

Treatment for brown recluse and hobo spider bites include:

• Daily cleaning with a povidone-iodine solution to prevent infection.
• Soaking the bite area in sterile saltwater (saline) solution three times a day.

What should I do if a spider bites me?

You should never attempt to suck out or remove venom from a spider bite. Instead, follow these steps:

1. Clean the bite area with warm water and soap.
2. Apply a cold, damp washcloth or an ice pack to the bite area.
3. Elevate the bite area.
4. Take an antihistamine (allergy medicine) to ease itching and swelling.
5. Take an over-the-counter pain reliever for pain and swelling.
6. Seek immediate medical attention for severe symptoms.

How is a spider bite diagnosed?

Seeing the spider is the best way to confirm both a bite and the type of spider. Otherwise, there isn’t a way to test for a spider bite or determine what bit you.

Your healthcare provider may make a diagnosis based on symptoms. Your provider may also send a sample of fluid from a blister to a lab to check for skin infections that cause similar symptoms, such as methicillin-resistant staphylococcus aureus (MRSA).