Black Widow Spider Bite
Medically reviewed by Drugs.com. Last updated on May 4, 2025.
What do I need to know about a black widow spider bite?
The venom from a black widow spider is poisonous. Symptoms of a reaction to the venom start about 30 minutes after the bite. Symptoms are usually mild and stop within a few days, but symptoms may be severe or last several days. Venom can spread and damage your muscles, nerves, or organs.
What are the signs and symptoms of a black widow spider bite?
- A sharp pain like a pinprick, or pain that spreads from the bite area to other areas
- Red, numb, tingling, stinging, or burning skin at the bite area
- A rash or itching at the bite area
- Swollen skin at the bite area, or swollen eyelids
- Muscle cramps or spasms, weakness, or trouble moving your legs
- Nausea or vomiting
- A cold sweat, or heavy sweating
- Trouble breathing
How is a black widow spider bite diagnosed?
Your healthcare provider will ask about your symptoms and examine the injured area. Your provider may ask about your medical history. You may need to have blood or urine tests or a skin biopsy. If you are able to capture the spider safely, bring it to your provider.
How is a black widow spider bite treated?
Treatment depends on how severe your symptoms are. You may need any of the following:
- NSAIDs , such as ibuprofen, help decrease swelling, pain, and fever. This medicine is available with or without a doctor's order. NSAIDs can cause stomach bleeding or kidney problems in certain people. If you take blood thinner medicine, always ask if NSAIDs are safe for you. Always read the medicine label and follow directions. Do not give these medicines to children younger than 6 months without direction from a healthcare provider.
- Prescription pain medicine may be given. Ask your healthcare provider how to take this medicine safely. Some prescription pain medicines contain acetaminophen. Do not take other medicines that contain acetaminophen without talking to your healthcare provider. Too much acetaminophen may cause liver damage. Prescription pain medicine may cause constipation. Ask your healthcare provider how to prevent or treat constipation.
- Muscle relaxers may be given to relieve cramps or spasms.
- A tetanus vaccine is a booster shot used to help prevent tetanus. Tetanus is a life-threatening bacterial infection that affects the nerves and muscles. The bacteria can be spread through spider bites.
- IV fluids may be needed to prevent dehydration and kidney failure.
- Antivenom may be given if your symptoms are severe or you are at increased risk for severe symptoms. Antivenom can help slow or stop your symptoms.
How do I manage a black widow spider bite?
- Elevate your wound above the level of your heart as often as you can. This will help decrease swelling and pain. Prop a bitten arm or leg on pillows or blankets to keep it elevated comfortably.
- Apply ice to your wound for 15 to 20 minutes every hour, or as directed. Use an ice pack, or put crushed ice in a plastic bag. Cover the bag with a towel before you apply it to the wound. Ice helps prevent tissue damage and decreases swelling and pain.
- Clean the wound with mild soap and water. Wash your hands before and after you take care of the wound. Pat the area dry. Do not rub the wound. Clean your wound as often as directed by your healthcare provider. Watch for more swelling, redness, or fluid oozing out. Apply gentle pressure to stop any bleeding.
How can I prevent a black widow spider bite?
- Recognize the spider. Two types of black widow spiders can be found in the United States. One has a black abdomen with a red hourglass shape on it. The other type may be brown or have red legs. It has a row of spots down the middle of the abdomen. The spots are usually red but may be yellow or white.
- Learn where to find them. Black widow spiders live in areas that are cool and dark. They can be found in sheds, garages, and attics.
- Use caution. Black widow spiders are not aggressive. They bite people only when threatened. Make noise when you enter attics or other spaces where spiders may live. Noise may scare them away. Use caution when you remove a web or spider.
- Be proactive. Clean out storage areas. Remove woodpiles and other outside areas, especially piles where spiders can live. Wear gloves, long sleeved shirts, pants, and shoes when you work near wood or piles.
Call your local emergency number (911 in the US) if:
- You have tremors or trouble breathing, talking, or walking.
- You have chest pain, tightness, or heaviness that may spread to your shoulders, arms, jaw, neck, or back.
When should I seek immediate care?
- You have severe abdominal pain.
- Your wound turns blue or black and smells foul.
- Your muscles become stiff and start to cramp or spasm.
- Your heart is racing.
When should I call my doctor?
- You have increased pain or a change in how your pain feels.
- You have a fever or a headache.
- Your wound is red, swollen, or draining fluid.
- Your eyes become sensitive to light.
- You have pain when you move the bitten body part, or the part is difficult to move.
- You get tender lumps in your groin or armpits.
- Your symptoms spread from the bite to other parts of your body.
- You have questions or concerns about your condition or care.
Care Agreement
You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.© Copyright Merative 2025 Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes.
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