What is the treatment for an infected spider bite (arachnidism)?

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From the Guidelines

For an infected spider bite, seek medical attention promptly as professional evaluation is essential. Cleaning the wound with soap and water, then applying an antibiotic ointment like bacitracin or neosporin and covering with a sterile bandage, changing it daily, is crucial for preventing further infection [ 1 ]. The patient may be prescribed oral antibiotics such as cephalexin (500mg four times daily for 7-10 days) or clindamycin (300mg four times daily for 7-10 days) if the infection is significant. Elevating the affected area and taking over-the-counter pain relievers like acetaminophen or ibuprofen as directed for discomfort can help alleviate symptoms [ 1 ]. It is essential to watch for signs of worsening infection, such as spreading redness, increased pain, pus, fever, or red streaks extending from the bite, which require immediate medical care.

Key Considerations

  • Identifying the spider, if possible, can help guide appropriate care, as certain species like brown recluse or black widow spiders can cause more serious reactions [ 1 ].
  • Emergency services should be called if a person bitten by a spider develops symptoms throughout the body, such as difficulty breathing, muscle rigidity, dizziness, or confusion [ 1 ].
  • A person bitten by a spider should seek medical care if pain extends beyond the site of the bite, becomes severe, and is not controlled by over-the-counter pain medications; if an open wound develops; or if the person experiences symptoms throughout the body [ 1 ].

Treatment Options

  • Over-the-counter acetaminophen and nonsteroidal anti-inflammatory agents can be used to alleviate local pain from spider bites [ 1 ].
  • Topical lidocaine can be useful to relieve local pain from spider bites if the skin is intact [ 1 ].
  • Ice can be useful for local pain relief from spider bites [ 1 ].

From the Research

Treatment for Infected Spider Bites

The treatment for infected spider bites, also known as arachnidism, typically involves a combination of surgical and medical interventions.

  • Aggressive surgical debridement of the infected area is often necessary to remove dead tissue and prevent further infection 2.
  • Intravenous antibiotics are also commonly used to treat infected spider bites, particularly those caused by methicillin-resistant Staphylococcus aureus (MRSA) 2.
  • Hyperbaric oxygen therapy (HBOT) has also been shown to be effective in treating nonhealing wounds caused by brown spider bites, even in the late, chronic stage 3.
  • In some cases, antivenom may be necessary to treat severe systemic reactions caused by certain spider bites, such as those from the black widow spider 4, 5.

Management of Spider Bites

The management of spider bites typically involves a clinical approach to diagnosis and treatment.

  • A thorough assessment of the patient's symptoms and medical history is necessary to determine the best course of treatment 4, 5.
  • Treatment may involve the use of analgesics, ice, compression, elevation, and antihistamines to manage symptoms such as pain and swelling 4.
  • In cases where the spider bite is suspected to have caused cytotoxic envenomation, management should be as recommended for other cytotoxic spider bites 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Spider bites - Assessment and management.

Australian family physician, 2009

Research

Spider bites.

The Journal of the American Board of Family Practice, 1995

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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