Symptoms and Signs of Black Widow and Brown Recluse Spider Bite

Doctor's Notes on Black Widow and Brown Recluse Spider Bite

Black widow spiders are found throughout the United States. They may be black or brown with a leg span of approximately one to two inches and a red hourglass marking on the abdomen. Black widow spider toxin causes nerve cell dysfunction and muscle cell twitching. Brown recluse spiders are found mainly in the south-central United States. They are tan to dark brown with a leg span of approximately 1 inch and many have a violin-shaped marking on the chest. Human contact with these spiders is usually accidental.

Symptoms of black widow spider bites result include

• a halo lesion consisting of a pale circular area surrounded by a ring of redness,
• a painful bite,
• numbness,
• tingling,
• rashes,
• sweating,
• nausea,
• vomiting,
• dizziness,
• cramps,
• rigid abdominal muscles,
• chest tightness,
• weakness,
• difficulty breathing, and
• high blood pressure.

Symptoms of brown recluse bites include

• tenderness,
• redness,
• local swelling,
• pain,
• itching,
• blisters, and
• symptoms of an allergic reaction.

Brown recluse bites eventually form large ulcers and may cause tissue necrosis (death of the tissue in the area of the bite). Other symptoms of brown recluse bites include

• fever,
• chills,
• rash,
• nausea, and
• vomiting.

More severe reactions include

• kidney failure,
• blood clotting problems, and
• difficulty breathing.
• Death can occur. 

What Is the Treatment for Black Widow and Brown Recluse Spider Bites?

Treatment of bites from black widow and brown recluse spiders depends on the severity of symptoms of the bite. 

In the case of a black widow spider bite, treatment consists of: 

• Clean the bite with soap and water
• Pain medication (bites are often painful)
  • Acetaminophen or ibuprofen
  • Stronger medications such as oral narcotics may be needed
• Muscle relaxers for muscle spasms
  • Benzodiazepines
  • Cyclobenzaprine
  • Baclofen
• Anti-nausea medications
• Intravenous fluids
• Tetanus booster if needed
• Cold packs to the area of the bites

Some black widow bites cause severe symptoms and require the patient to have intensive medical monitoring and treatment requiring hospitalization. Also, in general, antibiotics are prescribed only if there are signs of infection. 

In the case of a brown recluse spider bite, the treatment consists of:

• Clean the bite with soap and water.
• Apply cold packs
• Pain medication 
  • Over-the-counter (OTC) acetaminophen (Tylenol) or ibuprofen (Motrin, Advil)
• Give tetanus booster if needed

Antibiotics are not used in the initial treatment of brown recluse spider bites. Wounds should be closely monitored for signs of infection (redness, swelling, pus, or dark/black skin). Death of tissue in the area of the bite (dermal necrosis) can be a delayed presentation of a brown recluse spider bite. If it occurs, wound care specialists or surgeons may need to be consulted. 

There is an antivenom available for brown recluse bites but it is not available in the United States.