From the Guidelines
For most spider bites, treatment involves cleaning the bite with soap and water, applying an ice pack to reduce pain and swelling, taking over-the-counter pain relievers like acetaminophen or ibuprofen as needed, and using an antihistamine such as diphenhydramine to reduce itching. According to the 2024 American Heart Association and American Red Cross guidelines for first aid 1, spider bites and scorpion stings are common occurrences in the United States, and although many are benign, some species of spider can cause more severe localized and systemic symptoms.
Key Considerations
- The effects of spider and scorpion envenomation vary widely around the world, and these guidelines are relevant to spider bites and scorpion stings occurring in the United States and Canada 1.
- Emergency services should be called if a person bitten by a spider or stung by a scorpion develops symptoms throughout the body such as difficulty breathing, muscle rigidity, dizziness, or confusion 1.
- A person bitten by a spider or stung by a scorpion should seek medical care if pain extends beyond the site of the bite/sting, 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 scorpion stings 1.
- If the skin is intact, topical lidocaine can be useful to relieve local pain from scorpion stings 1.
- Ice can be useful for local pain relief from scorpion stings 1.
- A randomized trial of 130 adults with scorpion stings occurring in Turkey showed pain improvement with application of topical 5% lidocaine, administration of intravenous acetaminophen, or topical application of ice; the greatest pain reduction was from lidocaine 1.
Special Considerations
- Children, elderly individuals, and those with compromised immune systems should be monitored more closely after any spider bite.
- If the bite is from a black widow or brown recluse spider, or if symptoms worsen (increasing pain, spreading redness, fever, difficulty breathing, severe swelling), seek immediate medical attention 1.
From the Research
Treatment of Spider Bites
- Most spider bites are asymptomatic and require minimal treatment, but some species can cause significant morbidity and rarely, mortality 2, 3.
- For brown recluse spider bites, treatment includes thorough cleansing of the bite area and updating tetanus status as needed 4.
- Patients who develop systemic symptoms require hospitalization, and surgical excision of skin lesions is indicated only for lesions that have stabilized and are no longer enlarging 4.
- Steroids are indicated in bites that are associated with severe skin lesions, loxoscelism, and in small children 4.
- Dapsone should be used only in adult patients who experience necrotic arachnidism and who have been screened for glucose-6-phosphate dehydrogenase deficiency 4, 5.
- Topical nitroglycerin can be of value in decreasing the enlargement of necrotic skin ulcers 4.
- Hyperbaric oxygen therapy may also be used to treat necrotic wounds caused by brown recluse spider bites 5.
Specific Spider Bites
- Black widow spider bites can cause severe neurologic problems requiring the use of antivenin 3.
- Funnel web spider bite is a medical emergency, and a pressure immobilisation bandage should be applied and the patient transferred to a hospital with available antivenom and resuscitation facilities 2.
- Latrodectism (red back spider envenomation) is characterised by pain (local, radiating, and regional), and systemic symptoms occur less commonly 2.
Diagnosis and Management
- Diagnosis of spider bites can be difficult because the spider is not seen at the time of the suspected bite, and lay identification of the spider has not been shown to be reliable 2, 3.
- Capture of the offending spider appears to be most helpful in the diagnosis and proper treatment of spider bites 5.
- Clinicians must consider spider bite in the differential diagnosis of unexplained autonomic and neurological dysfunction, particularly in children 2.