Most spider bites heal on their own in about a week. The vast majority of spiders you’ll encounter produce bites no worse than a mosquito bite, with mild redness, swelling, and itching that fade within five to ten days. The timeline changes significantly, though, if the bite comes from a brown recluse or black widow, where healing can stretch from weeks to months.
Typical Bites From Common Spiders
The spiders living in most homes and gardens, including house spiders, cellar spiders, and garden spiders, produce bites that follow a predictable pattern. You’ll notice a small red bump within a few hours, sometimes with mild swelling around it. Itching tends to peak in the first day or two, then gradually fades. By day five to seven, the bump has usually flattened and the redness is nearly gone.
During that week, basic wound care is all you need. Wash the bite with soap and water, apply a cold pack or wet compress to bring down swelling, and keep the area clean. Over-the-counter antihistamines can help with itching. If you notice the redness shrinking day by day rather than expanding, that’s a normal healing bite doing its thing.
Brown Recluse Bites Take Much Longer
Brown recluse bites are a different category entirely because the venom destroys skin tissue. The bite itself often feels like a mild sting, easy to brush off. But over the next six to eight hours, the area becomes increasingly painful as blood flow to the tissue drops off. What started as a small red mark can darken and blister.
About a week or more after the bite, the damaged skin may turn black and form an open ulcer. This is the necrotic wound that makes brown recluse bites so notorious. These ulcers can take months to fully close, depending on their size and depth. Smaller wounds (under a few centimeters) tend to heal faster, while larger areas of tissue damage sometimes require medical procedures to help the skin close.
The more concerning scenario is when the venom triggers a body-wide reaction. Within the first 72 hours, some people develop fever, chills, nausea, joint pain, and a widespread rash. These systemic symptoms aren’t related to the size of the skin wound. A bite that looks relatively minor on the surface can still cause serious internal complications, so expanding pain, fever, or feeling generally unwell after a suspected recluse bite warrants immediate medical attention.
Black Widow Bites: Fast Pain, Variable Recovery
Black widow bites don’t typically cause the dramatic skin wounds that brown recluse bites do. Instead, the venom targets the nervous system, producing intense muscle cramping, abdominal pain, and sometimes chest tightness. These symptoms usually start within an hour of the bite and can feel alarming.
How long these symptoms last depends largely on treatment. In a review of 163 cases, patients who received antivenom saw complete symptom resolution in roughly 30 minutes on average. Those who didn’t receive antivenom experienced symptoms for an average of about 22 hours. The bite wound itself is small and heals like any minor puncture, usually within a week. It’s the muscle pain and cramping that make recovery feel longer.
Antivenom for widow bites can be effective when given up to 48 hours after the bite, with some case reports showing benefit even at 90 hours. So even if you don’t seek help immediately, treatment can still make a meaningful difference.
How to Tell if a Bite Is Getting Infected
The biggest concern with any spider bite during healing is secondary infection. A bite creates a small break in the skin, and bacteria can move in. The tricky part is that normal bite reactions, redness, swelling, a firm bump, look a lot like early infection. Here’s how to tell the difference.
- Normal bite reaction: The area itches more than it hurts. Redness stays roughly the same size or shrinks over days. You can see a small puncture point at the center. The skin around the bite feels firm but isn’t particularly warm.
- Possible infection: Pain becomes the dominant sensation rather than itch. Redness spreads outward over hours or days instead of staying contained. The skin feels hot to the touch. You develop a fever or see red streaking radiating from the bite.
A useful rule of thumb: if there’s itch but no real tenderness, infection is unlikely. If there’s growing tenderness and warmth without much itch, that pattern fits a bacterial skin infection rather than a normal bite healing on schedule.
What Affects Your Healing Timeline
Several factors can push healing faster or slower than the averages above. Your immune system plays a significant role. People with diabetes, circulation problems, or weakened immune systems tend to heal more slowly from any skin wound, spider bites included. Location matters too. Bites on the lower legs and feet, where blood flow is naturally slower, often take longer to resolve than bites on the arms or torso.
Scratching is probably the most common reason a simple bite takes longer than a week to heal. Breaking the skin open with your nails resets the healing clock and invites bacteria in. Keeping the area covered with a bandage during the itchiest phase (usually days one through three) helps you leave it alone.
If your bite hasn’t shown any improvement after seven to ten days, or if it’s actively getting worse after the first 48 hours, that’s enough reason to have it looked at. Most spider bites are unremarkable, but the ones that aren’t tend to declare themselves within that first week.