3. Redness and swelling
A spider bite can also cause the skin to become red and inflamed. That’s because your body is trying to protect itself from whatever foreign substances that the spider may have injected into your skin, even if those substances aren’t harmful. This also happens because your body is trying to heal the site of the bite.
The redness can vary from light to dark, and the swelling could be mild to moderate. If you are allergic to spiders, the swelling could become severe. A cold compress and an over-the-counter anti-inflammatory could reduce the redness and swelling. Still, you should consider seeing your doctor if you are particularly concerned, or if the redness and swelling to not subside within a few days, or get worse.