Almost all species of spiders do not intentionally bite humans, and when they do, it only because they’re provoked.
When a spider bites a person, the majority of these bites only create a very mild reaction in most people, like a minor swelling, an inflammation, or a bit of itching.
However, there’re some very poisonous spiders in North America which could be dangerous; even fatal at times. These poisonous species are densely found in the southern areas of America, but scientists have spotted black widow spiders in southern parts of Canada as well.
The venom with which these dangerous spiders utilise to paralyse, and eventually kill their prey, is quite harmful to humans too. Usually spider bites types vary, but if you’re bitten by an extremely venomous spider, you need to get treated ASAP as it could lead to severe local and systemic reactions in your body, which might even be fatal.
In the case of a black widow bite, or a brown recluse spider bite, medical attention should be urgent and immediate.