There are only a handful of small spiders that are poisonous. They are able to release poison when they bite and ingest a human. Spiders are the main predators of insects and they are feared by humans. If you come across a spider that is trying to attack you, you should immediately take precautions.
In the United States, there are three types of venomous spiders. These are funnel-web, black widow and brown recluse. The black widow is the most common of the three and it is found in the West Indies and North America.
It is estimated that more than 2,500 people have visited poison control centers each year because of the bites of the black widow. The bites are painful and may cause vomiting and diarrhea. Symptoms may include muscle rigidity and tremors.
The spiders are usually gray and look like a tangled web. When bitten, the venom can cause swelling at the site of the bite. Occasionally, it can also cause necrotizing lesions.
Unlike the black widow, the bite of the brown recluse does not lead to any fatalities. However, the venom of this spider can cause nausea and diarrhea.
Yellow sac spiders are another type of small spider that is poisonous. They are typically found in Mexico, South America and the United States. The venom is a cytotoxin that destroys cell function.
Grass spiders are another species that can be dangerous. This spider builds webs around your house and can also bite.