Black Widow Spider Bite

There are around 30,000 types of spiders and among them, the black widow spider is the most popular and the most dreaded one. There are many people who have an eternal fear of spiders. Spiders are blamed for many human woes such as if there is any local itching or rashes, people blame the spider, but the fact is spiders rarely bite human beings. In case of a bite from large spiders such as tarantulas, it can be very painful. In moderate regions, black widow and the brown recluse spiders need be feared. The black widow spider is a medium-sized spider with a half-inch long body. The mistaken belief that the female spider kills the male after mating has given it its name "black widow" spider.

Black Widow Spider Bite

Black Widow spiders get active at nighttime and prefer dark crevices or corners. They usually avoid human surroundings, but can be found in garages and outhouses. The female Black Widow infects humans only when she is disturbed and especially when she is with her eggs.

Signs and Symptoms of Black Widow Spider Bite

A protein venom is produced by the black widow spider and this venom affects the nervous system of the victim. The venom affects different people in different manner. Some victims are more affected by the venom than others. Symptoms commonly appear within 20 minutes to one hour after the spider has bitten. The first symptom is intense pain in the region where the spider has bitten; however, there may a mild reaction locally. After the intense local pain, victim or patient may experience localized or generalized abdominal pain, severe muscle cramps, tremor and weakness. The venom commonly affects the large muscle groups such as shoulder or back and causes significant pain. In more severe cases, patient may also experience nausea, vomiting, dizziness, fainting and chest pain. Respiratory difficulties may also occur. The intensity of the reaction depends on the victim's age and physical conditioning. Elderly people and children are more seriously affected than young adults. Sometimes, the symptoms can be misdiagnosed, such as abdominal pain resulting from this bite may be mistaken for appendicitis or gallbladder issues. Chest pain can be mistaken for a heart attack etc. Patients may also have increased blood pressure and heart rate. Increased blood pressure or hypertension may cause severe complications. Black widow's bite is rarely fatal. It is a cause of concern only if small children and elderly people are bitten.

Treatment for Black Widow Spider Bite

  • Cold, warm compresses and hot baths are recommended.
  • Over-the-counter pain killers such as ibuprofen and acetaminophen may also help.
  • If the pain is severe then narcotics for pain are needed.
  • Muscle relaxants given via injection also help.
  • The antivenin given for black widow spider bite is derived from horse serum. The venom of different species of black widow spiders is similar, so the antivenin which is made for one venom works for others too.
  • In severe cases, even narcotics don't relieve the symptoms. Some specialists recommend that antivenin should be used in severe cases as one vial of the antitoxin leads to substantial relief from symptoms. Antivenin is also recommended if there is delay in reaching the hospital. Whereas some experts advise using antivenin only in children and the elderly and in those individuals who have other severe medical conditions.
  • Horse serum-based antivenin has substantial risk of anaphylaxis, which is a severe and life-threatening allergic reaction. It is recommended that a skin testing be done on the patient before administering the serum. Another common side effect from horse serum is serum sickness where the patient develops fever, skin lesions, joint pain and swollen lymph glands. All these side effects are seen when the serum is given to treat rattlesnake bites and is rarely seen when treating black widow spider bites.
  • Patient should follow-up after the antivenin is given, as serum sickness may occur even after 7-12 days of administration of the antivenin. In a sensitive person, these symptoms may appear sooner. Serum sickness is self-limited and subsides on its own in 2-3 weeks. Antihistamines and steroids can be given for relief.
  • Prevention is better than cure. As the black widow spiders bite only if they are disturbed, people should be careful when they have to reach into dark corners or areas. Pest control service should be utilized in spider infested areas.
  • Serious complications from black widow spider bite are rare. Even if not treated with antivenin, symptoms last for many days then subside eventually and is rarely life threatening.

Written, Edited or Reviewed By:


Last Modified On: May 5, 2016

Pain Assist Inc.

Pramod Kerkar
  Note: Information provided is not a substitute for physician, hospital or any form of medical care. Examination and Investigation is necessary for correct diagnosis.

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