Most spider bites are harmless and heal on their own with basic first aid: clean the wound, apply a cool cloth, and take an over-the-counter pain reliever. The vast majority of spiders lack venom strong enough to cause anything worse than mild redness and swelling. That said, bites from a handful of species can cause serious symptoms, and any bite can become infected if not properly cared for. Here’s what to do step by step, what to watch for, and how to tell if something more serious is going on.
Immediate First Aid Steps
As soon as you notice a bite, wash the area with mild soap and water. Apply antibiotic ointment to the wound three times a day to help prevent infection. Then place a cool, damp cloth or a cloth-wrapped ice pack over the bite for about 15 minutes each hour. This reduces both pain and swelling during the first day.
If the bite is on an arm or leg, elevate that limb when you can. For itching, an over-the-counter antihistamine like diphenhydramine (Benadryl) or cetirizine (Zyrtec) helps. Calamine lotion or a hydrocortisone cream applied directly to the bite also calms itching. For pain, a standard over-the-counter pain reliever is usually enough.
How to Tell It’s a Spider Bite
Spider bites can look a lot like other insect bites or stings. They typically leave small puncture marks on the skin, sometimes two tiny dots close together, with redness and swelling around them. The sensation is often compared to a wasp sting. In many cases, people never see the spider and only notice the bite later, which makes it easy to confuse with a mosquito bite, flea bite, or even a small skin infection.
If you didn’t see a spider, don’t assume it was one. Many skin lesions blamed on spiders turn out to be bacterial infections. The key distinction: spider bites typically drain clear fluid, while bacterial infections (including MRSA) usually drain pus. If you did see the spider, try to remember its size, color, and markings, or snap a photo. That information helps with treatment decisions if symptoms worsen.
Black Widow Bites
Black widow bites cause painful swelling at the site, followed by cramps, muscle spasms, and body aches. Nausea is common. These symptoms tend to worsen over the first 12 hours, then gradually improve. Full resolution of pain can take anywhere from a few days to several weeks.
Severe black widow bites are treated in a hospital setting with pain medication and muscle relaxants, though muscle spasms from these bites often respond poorly to standard muscle relaxants. Antivenom exists and is most effective when given early, but it can still help up to 36 hours after the bite. Death from black widow bites is rare, but lingering symptoms can persist for weeks or even months in some cases, which is why medical evaluation matters if you develop anything beyond mild local pain.
Brown Recluse Bites
Brown recluse bites follow a more predictable visual timeline. Within three to eight hours, the bite site becomes red, sensitive, and feels like it’s burning. It may develop a bullseye pattern or turn a bruised, bluish color.
Between three and five days, if the venom has spread beyond the initial area, an ulcer forms at the bite site. In severe cases, the skin around that ulcer breaks down over the next one to two weeks, creating a wound that can take months to fully heal. By about three weeks, most bites that aren’t severe will have healed, with a thick black scab covering the wound.
Beyond the skin damage, brown recluse venom can cause systemic symptoms: fever, chills, rash, dizziness, vomiting, and difficulty sleeping. If you suspect a brown recluse bite and develop any combination of these, seek medical care promptly.
Signs the Bite Is Getting Worse
The biggest risk with any spider bite isn’t usually the venom itself. It’s secondary infection. Bacteria can enter through the broken skin and cause cellulitis or, in some cases, a staph infection including MRSA. Watch for these warning signs in the days after a bite:
- Increasing redness that spreads beyond the original bite area rather than shrinking
- Pus or cloudy drainage from the wound (clear fluid is normal, pus is not)
- Warmth and tenderness that intensifies rather than fading
- Fever, which is a major red flag for infection spreading beyond the skin
An MRSA infection can spread from the initial wound to surrounding skin, other parts of the body, or even the bloodstream and bones. A wound that keeps growing, starts oozing pus, or becomes increasingly painful and inflamed warrants medical attention, especially if you develop a fever alongside it.
What Recovery Looks Like
A typical, non-venomous spider bite improves noticeably within a few days. Redness and swelling peak in the first 24 to 48 hours, then fade. You may have mild itching or tenderness for up to a week.
Black widow bite symptoms generally peak around 12 hours and then begin improving, though full recovery can stretch to several weeks. Brown recluse bites have the longest recovery window. Most heal within three weeks, but bites that develop ulcers or significant skin breakdown can take several months to close completely, sometimes requiring wound care follow-up.
During recovery from any spider bite, keep the area clean and continue applying antibiotic ointment. Resist the urge to scratch or pick at the wound, which introduces bacteria and slows healing.
Preventing Spider Bites
Most spider bites happen when a spider is accidentally pressed against skin, often inside clothing, shoes, bedding, or gloves that have been sitting undisturbed. A few habit changes significantly reduce your risk.
Shake out shoes, clothing, and gloves before putting them on, especially items stored in garages, sheds, or closets you don’t open often. Check bedding before climbing in if your home is in an area where venomous spiders are common. If a spider lands on you, brush it off gently rather than crushing it against your skin, which is what causes most defensive bites.
Around your home, clear out clutter that gives spiders places to hide: old furniture, stacked newspapers, piles of clothes on the floor, unused tires. Spiders favor low-lying, undisturbed spots like wood piles, rock piles, barbecue grills, and the undersides of eaves. Seal cracks and gaps around doors, windows, and foundations to reduce entry points. Wear gloves and long sleeves when working in garages, sheds, attics, or outdoor storage areas where spiders are likely to set up.
For high-risk areas like known black widow webs, outdoor entry points, attics, and wood piles, targeted insecticide sprays can provide an additional layer of protection. If you have young children, check outdoor toys for spiders before bringing them inside or letting kids play with them.