The sting of the black widow can usually cause sharp, severe pain, but sometimes it may be pain-free.
There can be seen one or two red spots caused by the bite of poisonous teeth.
There could be redness, swelling and inflamed lymph nodes.
The sting causes severe muscle cramps, nausea, vomiting and high blood pressure.
The patient urgently needs assistance. Hospitals who have an antidote must be easily accessible.
If you manage to catch the spider, bring it with you for identification.