How do you tell a spider bite from an insect bite?
Q. How do you tell a spider bite from an insect bite — and how do you know if you’ve been bitten by something dangerous?
A. Spider and insect bites can be annoying and even painful, but Jonathan Edlow, vice chair of the department of emergency medicine at Beth Israel Deaconess Medical Center, says that they rarely pose a serious threat to health. This includes the vast majority of spider bites.
Edlow says that the most common dangerous spider in this region is the brown recluse spider, but those bites are very rare. “In 30 years, I’ve seen maybe one or two,’’ he says. Warning signs to look for are sharp pain, skin that turns red and blue, a blister that turns into an ulcer, and destruction of the tissue around the bite. Black widow spiders are the other common species with a serious bite. The bite itself often feels like a pinprick and leaves small reddish marks; a few hours later, however, it leads to pain, stiffness, nausea, fever, and abdominal pain. Both of these bites are serious and in rare cases life-threatening, and require medical attention.
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It’s difficult to know for sure whether you’ve been bitten by a spider and what kind, unless you happen to catch the spider in the act. Many people mistakenly assume they’ve been bitten by a spider when they have some other kind of bite or infection, and studies have found that even medical professionals overdiagnose spider bites, particularly brown recluse bites. Edlow says that the most common attacks he sees this time of year are bee stings and tick bites.
Most bites, whether from spiders or insects, do not require medical attention; they should be washed or cleaned with an antiseptic and treated with over-the-counter remedies to relieve pain or itching if needed. Edlow also recommends using an ice pack on any bite, to help decrease blood flow around the wound and slow the progression of symptoms. “The reality is that the vast majority of these things are not serious and are not going to lead to any disease,’’ Edlow says. “It’s summertime, and it’s good to be outside.’’