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Symptoms and Signs of How Serious Is a Black Widow Spider Bite?

Doctor's Notes on How Serious Is a Black Widow Spider Bite?

The signs and symptoms of the black widow spider bite usually begins with acute pain at the site of the bite. Other symptoms usually start about 20 minutes to one hour after the bite. The bite itself begins with two small dots. Local pain at the bite site is followed by localized general severe muscle cramps, abdominal pain, weakness and/or tremors. Severe signs and symptoms are nausea, vomiting, fainting, dizziness, chest pain and respiratory difficulties. However, people rarely die from a black widow spider bite.

The spider itself is a sign; black widow spiders are black with a reddish hour-glass shape on its body; if the spider can be captured or killed safely, it should be brought to the emergency department and will help identify the bite source.

The cause of the spider bite signs and symptoms is due to a protein venom secreted during the spider bite. Symptoms are severe; antivenin can help reduce symptoms.

Medical Author:
Medically Reviewed on 3/11/2019


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.