A number of spiders can cause spider bites that are medically important. Almost all spiders produce venom but only a few are classified as "venomous" and able to cause significant harm to humans. Others have a limited distribution. Medical reports have been criticized for poor evidence. In the last century, both white tailed and wolf spiders were considered medically significant, only to be recanted.
List of medically significant spider bites
Redback spider - Wikipedia
According to the Chinese Spider Database, there are 3, species of spiders in China today. Of these, only a few have been discovered to be venomous to humans. Most are found in the northernmost and southernmost regions of China, where climates are tropical. The Chinese bird spider Haplopelma schmidti is a type of tarantula found in southern China and Vietnam and is considered extremely aggressive and highly venomous. The venom of the Chinese bird spider is a neurotoxin that causes severe nerve damage, rendering the victim incapable of moving, and sometimes causing death if not treated. It captures its food by hiding and emerging from earthen burrows that can be up to several feet deep. Despite its name, the Chinese bird spider mostly dines on small rodents and insects.
The world's most dangerous spiders (WARNING GRAPHIC IMAGES)
Since spiders willfully inject toxins, they are considered venomous. Though the toxicology is complicated, we present the title of most venomous spider in the world so you can justify your fear of all spiders by identifying the deadliest eight-legged creeper. Atrax robustus , also known as the Sydney funnel web spider, has venom so potent, it can kill in just 15 minutes. Male funnel web spiders only grow to be a couple inches across, but they build their namesake funnel webs up to two feet underground.
Though most people have a big fear of spiders, it seems that venomous spiders are not such a big threat to humans as many people believe. First of all, studies have shown that most serious bites attributed to spiders were, in fact, due to other causes, notably other arthropods. Secondly, antivenin against spider bite has become very effective and thus made the occurrence of death resulting from a spider's bite a very rare thing. Lastly, spider venom, in general, is usually almost harmless to humans, since it evolved for capturing or killing small invertebrates and not big mammals like ourselves.