What are the symptoms and treatment of a bite from a spider (arachnid)?

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Last updated: February 28, 2025View editorial policy

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From the Guidelines

If you suspect a spider bite, seek medical attention immediately if you develop severe symptoms such as difficulty breathing, muscle rigidity, dizziness, or confusion, as these can be life-threatening. According to the 2024 American Heart Association and American Red Cross guidelines for first aid 1, emergency services should be called if a person bitten by a spider develops symptoms throughout the body.

Symptoms of a Spider Bite

The symptoms of a spider bite can vary depending on the type of spider, but common symptoms include:

  • Local pain at the site of the bite
  • Redness and swelling
  • Itching
  • Muscle cramps

Treatment of a Spider Bite

For mild symptoms, over-the-counter pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) can be used to alleviate local pain 1. Additionally, ice can be applied to the affected area to reduce swelling and pain.

When to Seek Medical Attention

However, if the pain extends beyond the site of the bite, becomes severe, and is not controlled by over-the-counter pain medications, or if an open wound develops, medical care should be sought 1. It is also important to seek medical attention if symptoms such as difficulty breathing, muscle rigidity, dizziness, or confusion occur, as these can be signs of a severe reaction.

Prevention

Prevention includes wearing gloves when working in areas where spiders may hide, shaking out clothing and shoes before wearing, and keeping your home free of clutter. By taking these precautions and seeking medical attention if necessary, the risk of serious complications from a spider bite can be minimized.

From the Research

Symptoms of Spider Bites

  • Most spider bites result in a solitary papule, pustule, or wheal 2
  • Systemic symptoms can accompany envenomation of certain spiders, including widow, funnel web, and Phoneutria spiders, and less often, those of recluse spiders 2
  • Brown recluse spider bites can result in necrotic skin ulcers (necrotic arachnidism) and systemic symptoms referred to as loxoscelism 3
  • Latrodectism (red back spider envenomation) is characterized by pain (local, radiating, and regional) and systemic symptoms occur less commonly 4
  • Funnel web spider bite is a medical emergency and can cause significant morbidity and rarely, mortality 4
  • Severe systemic symptoms have also been reported, including angioedema, hemolytic anemia, skin necrosis with superimposed bacterial infection or disseminated intravascular coagulation 5

Treatment of Spider Bites

  • Most bites should be thoroughly cleansed and tetanus status updated as needed 3
  • Patients who develop systemic symptoms require hospitalization 3
  • Surgical excision of skin lesions is indicated only for lesions that have stabilized and are no longer enlarging 3
  • Steroids are indicated in bites that are associated with severe skin lesions, loxoscelism, and in small children 3
  • Dapsone should be used only in adult patients who experience necrotic arachnidism and who have been screened for glucose-6-phosphate dehydrogenase deficiency 3
  • Topical nitroglycerin can be of value in decreasing the enlargement of necrotic skin ulcers 3
  • Management of spider bites is based on symptoms, and in severe cases, antibiotics, steroids, blood transfusions, and plasma exchange may also play a role 5
  • A pressure immobilisation bandage should be applied to funnel web spider bites and the patient transferred to a hospital with available antivenom and resuscitation facilities 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Brown recluse spider bites.

The Journal of the American Board of Family Practice, 2000

Research

Spider bites - Assessment and management.

Australian family physician, 2009

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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