It is the bite of only the adult female black widow spider that can be harmful to humans. Generally, a female black widow is withdrawn and timid, but at times, she will attack, such as after laying eggs or guarding them.
A black widow's bite feels like a needle puncture in the skin, but sometimes, a victim may not feel anything. Initially, the person may only observe evidence of the bite, including swelling and two tiny red spots where the fangs pierced the skin. Nonetheless, the victim usually feels pain pretty quickly, and it can last for a few days. Symptoms of a black widow bite may include nausea, fever, increased blood pressure, pain in the abdomen, back or limbs, as well as excessive sweating. In severe cases, paralysis may occur.
The venom of a black widow is a neurotoxin, which means it is toxic to a person's nervous system. People's reactions to bites can vary, depending on such factors as an individual's sensitivity, or the location and depth of the bite. Elderly people and young children are at greater risk, as are people with heart problems, compromised immune systems, or poor overall health.
If treated, these bites are rarely fatal, and there is an anti-venom available for black widow bites. If you or another person is bitten, immediately seek the attention of a doctor or visit the nearest emergency room. If possible, take the spider along for identification, even if it is not fully intact.