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The Long-Term Effects of Black Widows

| Updated September 26, 2017

Although black widows rarely kill people, a single drop of their venom is more dangerous "per drop than any other creature in North America," according to the National Outdoor Leadership School Wilderness Medicine Institute. For most individuals, a black widow spider bite results in short-term mild discomfort, cramping and pain and swelling around the bite area. Severe, long-term effects are rare.


Common effects of the black widow bite include severe cramping and stiffness in the abdominal area. Other short-term symptoms may include nausea, fever, sweating, tremors, difficulty breathing, increased blood pressure, anxiety and restlessness. According to Ask the Exterminator, it is rare for the black widow spider's bite to cause serious long-term complications or death. Anyone who experiences whole-body symptoms or is at risk of high blood pressure or cardiac problems should call 911.


Despite the venom's raw powerfulness, several variables can affect its potency when a person is bitten. The location of the bite and proximity to the bloodstream, as well as how much venom is injected, can largely determine how quickly and severe the venom affects a person. Also, those who are in poor health or are old or young are more susceptible to the venom. Those who have heart conditions also are susceptible to more serious symptoms of envenomation.


In some cases, victims may not even notice they have been bitten and may not experience any severe symptoms or pain or swelling in the bite area. However, if a reaction is occurring, victims are advised to stay calm and seek medical attention. It's important to clean the bite area with soap and water and apply a cool compress over the bite while elevating the bite area above the heart, if possible. Those who have a history of high blood pressure or cardiac problems should seek immediate medical attention as soon as they realize they have been bitten.

Duration of Symptoms

According to CalPoison, severe muscle pain and cramps typically develop within the first two hours after a bite. Victims who are at high risk of experiencing serious health problems may require an overnight stay, testing and observation at a hospital. Symptoms typically diminish or go away entirely within three to four days.

Characteristics of Black Widow Spiders

Black widow spiders are nocturnal and are most active during the nighttime. Female southern black widows have an hour-glass on the underside of their abdomen while northern black widows have a row of red spots in the middle of the abdomen with two crosswise bars on the underside of the abdomen (Web MD). Black widows typically live in wood piles, underneath logs, in utility sheds and other outbuildings. Other habitat areas include stone crevices or large piles of vegetation.