How dangerous is the black widow spider?

The vast majority of spiders pose no threat to humans.

Of the approximately 48,000 known spider species globally, fewer than 30 are truly medically significant to humans.

In China, a small number of medically important spiders include: the black widow spider (Latrodectus, also known as "red-spot widow") — found in southern China; its venom contains a potent neurotoxin (α-latrotoxin), and a bite can cause severe pain, muscle spasms, and systemic symptoms, but antivenom is effective and the mortality rate is extremely low.

The brown recluse spider (Loxosceles) may be limited to the border regions of Yunnan in China; its venom contains cytotoxins that can cause local tissue necrosis.

Yellow sac spiders (Cheiracanthium) are relatively widely distributed in China; their bite can cause local redness, swelling, and pain, but it is usually not serious.

The vast majority of cases diagnosed as spider bites are actually bites from other insects (such as ticks, bed bugs, or fleas) misattributed to spiders — this misdiagnosis is very common.

If you did not witness the spider biting you at the exact moment, the bite wound is very likely unrelated to spiders.