From the Guidelines
For treatment of Latrodectus mactans (black widow) envenomation causing abdominal muscle spasms, antivenom (Antivenin Latrodectus mactans) may be considered in severe cases, but the primary treatment focuses on pain management and muscle relaxation with medications such as opioid pain medications and muscle relaxants. The primary treatment for Latrodectus mactans envenomation focuses on alleviating symptoms, particularly pain and muscle spasms. According to the expert consensus guidelines for stocking of antidotes in hospitals that provide emergency care 1, the treatment approach should prioritize pain management and muscle relaxation.
Treatment Approach
- Pain management: Opioid pain medications such as morphine or hydromorphone may be prescribed for severe pain.
- Muscle relaxation: Muscle relaxants like methocarbamol or diazepam can be used to alleviate muscle spasms.
- Calcium gluconate: This may be administered intravenously to help alleviate muscle cramping, as noted in the guidelines for stocking of antidotes in hospitals 1.
Antivenom Consideration
In severe cases, antivenom (Antivenin Latrodectus mactans) might be considered, but it's used cautiously due to potential allergic reactions. The guidelines suggest stocking 1 vial of Antivenin (Latrodectus mactans) for treatment 1.
Supportive Care
Supportive care includes:
- Intravenous fluids
- Monitoring vital signs
- Tetanus prophylaxis if needed
- Applying ice to the bite site to reduce local pain and swelling Symptoms usually resolve within 24-48 hours with treatment. The venom affects nerve endings, causing the release of neurotransmitters that lead to muscle spasms, which is why muscle relaxants are effective. Always have the spider identified if possible to confirm the species and guide treatment.
From the FDA Drug Label
Diazepam is a useful adjunct for the relief of skeletal muscle spasm due to reflex spasm to local pathology (such as inflammation of the muscles or joints, or secondary to trauma), spasticity caused by upper motor neuron disorders (such as cerebral palsy and paraplegia), athetosis, and stiff-man syndrome
The treatment for Latrodectus mactans (black widow) envenomation causing abdominal muscle spasms may include diazepam (PO) as an adjunct for the relief of skeletal muscle spasm. However, the FDA label does not explicitly state its use for black widow envenomation.
- Key consideration: Diazepam may be useful for relieving muscle spasms, but its effectiveness for this specific condition is not directly addressed in the label 2.
From the Research
Treatment for Latrodectus mactans Envenomation
The treatment for Latrodectus mactans (black widow) envenomation causing abdominal muscle spasms includes:
- Pain relief with IV opioids and muscle relaxants, such as benzodiazepines 3, 4
- Administration of black widow spider-specific antivenin, which has been shown to be effective in relieving symptoms and shortening the duration of envenomation 3, 5, 6, 7
- Use of analgesics and muscle relaxants as adjuvant treatment 7
- Intravenous calcium, although its effectiveness has been questioned in some studies 3
Effectiveness of Treatment Options
- Black widow spider antivenom has been shown to be effective in relieving symptoms and shortening the duration of envenomation, with complete resolution of symptoms in a mean time of 31 minutes 3
- IV opioids and benzodiazepines have been shown to be effective in relieving pain and easing muscle spasms in most patients with latrodectism 4
- Calcium gluconate has been found to be ineffective in providing symptomatic relief in some studies 3