Most spider bites are NOT dangerous. Most bites cause mild redness and swelling that clears up on its own. Many of the more severe images in our collection are the result of delayed treatment or an allergic reaction, not the venom itself.
What does a bite with a red line mean?
A red line extending from a bite site is a warning sign that should not be ignored. It usually indicates lymphangitis – a condition where bacteria have entered the lymphatic vessels near the bite and are spreading through the body. This is a sign of infection, not venom. If you notice a red line extending from your bite, go to the emergency room the same day. Left untreated, the infection can spread rapidly and cause life-threatening complications including sepsis. While waiting for medical attention, keep the area clean and do not scratch or pick at the bite as this introduces more bacteria into the wound.
What does a bite with a red circle mean?
A red circle around a bite does not automatically mean a spider bit you. If the mark keeps expanding into a bull’s-eye pattern, that points more toward a tick-related rash than a typical spider bite.
If you see that kind of spreading ring, or you start feeling sick along with the rash, get medical advice the same day. For spider bites, what matters more is whether the area is staying local, getting infected, or developing severe pain, swelling, or a red line moving away from the wound.
Compare your bite to our photo library
Browse the photos above to compare what you are seeing. If you are still unsure what bit you, browse our dangerous spider identification guides or check the brown recluse spider bite page for more specific photos and symptoms.