Spider Bite

Is this your symptom?

• Spider bite (North America)
• Or, there are bite symptoms (redness, pain, swelling) and a spider was seen nearby

Some Basics...

• There are over 20,000 species of spiders in the world. Most of these spiders cause harmless bites in humans.
• In the United States, there are two species that cause serious bites in humans. These are the black widow ( Lactrodectus ) and the brown recluse ( Loxosceles ).
• If you see your doctor, bring the spider along in a jar for identification. Brown recluse spiders are very hard to identify.
• Sometimes people wrongly believe that they have had a spider bite. Instead, they may have a skin infection with bacteria called Staphylococcus aureus (MRSA).
• Tetanus shot may be needed if you are not fully protected against tetanus (received less than 3 shots). You will also need a tetanus booster if it has been longer than 10 years since your last one.

Black Widow Spider Bite

• Description: a shiny, jet-black spider with long legs. The total size of the spider is 1 inch (25 mm). It may have a red or orange hourglass-shaped marking on its underside. This will not be on all spiders of this species.
• Habitat: found throughout North America. They are not found in Alaska or the far North.
• Symptoms - Bite Wound: the bite causes moderate to severe pain right away. There is most often little to no reaction at the bite.
• Symptoms - Systemic: severe muscle cramps within 1- 6 hours. These will last 24-48 hours. Other symptoms include stomach pain, vomiting, restlessness, high blood pressure, and weakness.
• Treatment - Wound Care: wash bite with soap and water. Put an ice pack on the bite.
• Treatment - Medications: parenteral analgesics may be needed for pain and benzodiazepines for muscle spasms. There is an anti-venom that is used for severe symptoms, seizures, or very high blood pressure.
• What to Expect: symptoms most often go away in 2-3 days. These bites rarely cause death. A bite is more serious in a small child, as are multiple bites.
• Special Note: many bite wounds are "dry bites." This means that no poison was injected into skin.

Brown Recluse Spider Bite

• Also known as the "violin" or "fiddleback" spider.
• Description: a brown spider with long legs. The total size of the spider is ½ inch (12 mm). It has a dark violin-shaped marking on top of its head. This will not be on all spiders of this species.
• Habitat: found in the Southern, Southwestern and Midwestern United States.
• Symptoms - Bite Wound: the spider's poison causes cell destruction and blood cell breakdown. The bite is first painless or minimally painful. There will be pain and blisters at the bite within 4-8 hours. The middle becomes bluish and crater-like over 2-3 days. The skin inside the crater may die. This is called a necrotic ulcer.
• Symptoms - Systemic: these include fever, vomiting, and muscle aches. There are no life-threatening symptoms.
• Treatment - Wound Care: wash bite with soap and water. Put a cold pack on the bite.
• What to Expect: most necrotic ulcers heal over 1-8 weeks. Scarring happens to 10-15% of bites. Skin damage sometimes needs skin grafting.

Hobo Spider Bite

• Also known as the funnel-web spiders.
• Description: a brown spider with long legs. Size is about ½ to ¾ inch (12-20 mm). Appearance varies, it is often hard to identify.
• Habitat: found in North America.
• Symptoms - Bite Wound: generally considered harmless, despite their somewhat larger size. A bite may be painful and mildly swollen for 1 or 2 days (much like a bee sting).
• Symptoms - Systemic: none.
• Treatment - Wound Care: wash bite with soap and water. Put a cold pack on the bite.
• What to Expect: bite wounds heal completely.

Tarantulas

• Habitat: tarantulas are found in the Southern United States (like the Desert Southwest).
• Symptoms - Bite Wound: mild stinging with a little swelling at the bite. The bite does not cause skin tissue to die.
• Symptoms - Eye: some tarantulas have hairs that can come off. Like a fiberglass fragment, they can penetrate skin and cause itching and redness. If they lodge in the eye, they can cause eye problems.
• Symptoms - Systemic: none.
• Treatment - Wound Care: clean the bite wound with soap and water. Put a cold pack on it and take pain medicine. Get a tetanus booster if it has been more than 10 years since last shot.
• Treatment - Eye Irritation: see an eye doctor if you have irritation or redness after handling a tarantula. The doctor will perform a slit lamp exam of the eye.
• What to Expect: bite wounds fully heal. Eye problems often go away under the care of an eye doctor.

Minor (Non-Dangerous) Spider Bites

• More than 50 spiders in the United States and Canada have poison. They can cause minor, non-serious reactions. Single, unexplained painful bites that happen during the night can be from spiders.
• Symptoms - Bite Wound: the bites are painful and mildly swollen for 1-2 days. They may look like a bee sting.
• Symptoms - Systemic: none.
• Treatment - Wound Care: clean the bite wound with soap and water. Put a cold pack on the bite and take pain medicine.
• What to Expect: bite wounds fully heal.