After a woman in Chicago was bitten by a yellow sac spider, her fingers were swollen and her fingers turned purple and porcelain white. About 36 hours after the spider bite, the 53-year-old was in a dermatology clinic. At that time, the fifth finger of her right hand was discolored and painful.

Yellow sac spiders are widely distributed throughout the United States. They are found in the garden during the warm season, and when it gets cold in autumn, they enter the room. They are active hunters, so they look for prey instead of building a network to capture it. Yellow sac spiders can be identified by their yellow body and brown fangs. They are very small, less than a centimeter (less than half an inch) in length.

There are two types of yellow sac spiders in the United States-Cheiracanthium Moldei and Cheiracanthium inclusum. The former was introduced from Europe in the 1940s, and C. inclusum is a native species.

As we all know, yellow sac spiders can bite people. Michigan State University stated that these spiders have been bitten by humans more than any other species in the United States. It says that they are "easy to bite" and "it has been observed that they crawl on the surface of human skin and bite for no reason."

In a yellow sac spider bite case report published in the New England Journal of Medicine (NEJM), Adam S. Cifu and Sarah L. Stein from the University of Chicago recorded a case where a female was bitten and successfully treated. Take the spider to the clinic. She was examined and found that her fingers were red with a "dark center". She was treated with painkillers and applied ointment, but the discoloration was more serious the next day, and her fingers were swollen and "very soft". After six days, the swelling disappeared, but the skin became purple and porcelain white.

Stein told Newsweek that she rarely treats yellow sac spider bites. "Patients usually have inflamed isolated lesions, which they attribute to'spider bites', but they don't have spiders, and they haven't seen spiders," she said. "Due to common bacterial infections, these lesions are usually local abscesses."

Stein said this response is typical of yellow sac spiders. She said that if people think they were bitten by a yellow sac spider, anti-inflammatory and painkillers would help. She also said to use petroleum jelly ointment and bandages to protect the area.

The woman recovered completely two weeks after the first bite. The case report concluded: "Spiders usually bite people who are sleeping or dressing. The bite causes local pain, redness and swelling, and usually does not progress to necrosis as in this case."

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