Cleaning a bite wound immediately and thoroughly is the single most important thing you can do to prevent infection. Run clean water over the wound for at least five minutes, gently washing with mild soap to flush out bacteria. After that, the next steps depend on the type of bite, where it landed on your body, and how deep it is. Most bite wounds need professional medical evaluation, even when they look minor on the surface.
Clean the Wound Right Away
Bite wounds introduce bacteria deep into tissue, so irrigation (flushing with water) is your first priority. Hold the wound under running tap water or pour clean water over it steadily for five to ten minutes. Use regular soap around and in the wound. You don’t need high-pressure devices or special antiseptic solutions. Research published in the New England Journal of Medicine found that very low pressure irrigation with normal saline worked just as well as high-pressure methods for preventing complications, and that soap solutions actually led to slightly worse outcomes than plain saline in wound healing. Plain water and gentle soap are enough.
After flushing, apply gentle pressure with a clean cloth to stop any bleeding. Once the bleeding slows, cover the wound loosely with a clean bandage. Don’t seal it tightly or try to close it with butterfly strips or adhesive closures. Bite wounds are generally left open rather than stitched shut because closing them can trap bacteria inside the tissue and dramatically increase infection risk. Facial bite wounds are sometimes an exception because of cosmetic concerns, but that decision belongs to a doctor.
Why the Bite Source Matters
The animal (or person) that caused the bite determines which bacteria you’re dealing with and how aggressively the wound needs to be treated.
Cat bites are the most infection-prone of common animal bites. Cats have thin, sharp teeth that create deep puncture wounds, essentially injecting bacteria straight into tissue, tendons, or joints. The primary concern is a fast-growing bacterium called Pasteurella multocida, which causes rapid swelling, redness, and pain. In one study of 55 patients with infected animal bites to the hand, 72% were from cats. Infection after a cat bite typically shows up fast: within 24 hours in about 70% of cases, and within 48 hours in nearly 90%. If a cat bites your hand or wrist, you should treat it as a medical visit situation, not a wait-and-see situation.
Dog bites account for 80 to 90% of all mammalian bites. They tend to cause more crushing and tearing of tissue compared to the neat punctures of cat bites. Dog bites carry a mix of bacteria, though infection rates are somewhat lower than cat bites because the wounds are more open and easier to clean. Deep dog bites, especially on the hands, still carry serious infection risk.
Human bites are more dangerous than most people realize. About one-third of human bite wound infections involve a bacterium called Eikenella corrodens, which is resistant to several common antibiotics. A specific type of human bite, the “fight bite” or clenched fist injury (when a person punches someone in the mouth and the teeth cut the knuckles), is particularly dangerous. The wound may look like a small cut, but the tooth can penetrate the joint capsule when the fist is clenched. One study found that 62% of wounds overlying the knuckle joints had actually penetrated into the joint itself. These injuries need surgical exploration.
When You Need Medical Care
Certain bite wounds always warrant a visit to urgent care or the emergency room, regardless of how they look on the surface:
- Bites on the hands or feet. Infections in the hand are the most common complication of mammalian bites and are more likely to require surgery than bites elsewhere on the body. Hands have tendons, joints, and small compartments where bacteria thrive.
- Puncture wounds. If the teeth penetrated deeply, you can’t adequately clean the wound at home.
- Bites near or over a joint. These risk penetrating into the joint space, which can lead to septic arthritis.
- Cat bites anywhere on the body. The infection rate is high enough that most cat bites warrant prophylactic antibiotics.
- Human bites. Especially any wound on the hand from contact with teeth.
- Bites to the face or genital area. These require professional wound management.
- Any bite that won’t stop bleeding or has visible damage to deeper tissue.
Who Faces Higher Risk of Complications
Some people are more vulnerable to serious infections after a bite wound. If you have diabetes, the risk is substantially higher. One study found that diabetic patients with infected hand bites had a 48% chance of eventually requiring amputation, compared to 5% in non-diabetic patients. Diabetic peripheral neuropathy can also mask the pain that would normally prompt someone to seek care quickly, allowing infection to progress.
Other high-risk groups include people taking immunosuppressive medications (such as steroids or drugs for autoimmune conditions), those who’ve had a splenectomy, people with liver disease or cirrhosis, heavy alcohol use, and anyone at the extremes of age. Elderly patients are more likely to suffer hand injuries from bites and more often need surgery and hospitalization. If you fall into any of these categories, don’t wait to see if the wound looks infected. Go to a doctor the same day.
Antibiotics for Bite Wounds
Not every bite wound requires antibiotics, but many do. Doctors typically prescribe preventive antibiotics for moderate or severe bites, puncture wounds, bites to the hands or feet, bites near joints, and bites in immunocompromised patients. The standard first-line treatment is amoxicillin-clavulanate, a combination antibiotic that covers the broad range of bacteria found in animal and human mouths, including the Pasteurella species from cat and dog bites and the Eikenella species from human bites.
If you’re allergic to penicillin, your doctor will choose an alternative combination. The key point is that ordinary amoxicillin alone is not sufficient for bite wounds because it doesn’t cover the full range of bacteria involved.
Tetanus and Rabies Concerns
Bite wounds are considered “dirty” wounds for tetanus purposes. According to CDC guidelines, you need a tetanus booster if you’ve completed your primary vaccine series but your last shot was five or more years ago. If your vaccination history is unknown or incomplete, you’ll need both a tetanus vaccine and tetanus immune globulin.
Rabies is the other major concern, particularly with wild animal bites or bites from unvaccinated domestic animals. Rabies is nearly 100% fatal once symptoms appear, but completely preventable with timely treatment. Post-exposure prophylaxis for someone who hasn’t been previously vaccinated involves both rabies immune globulin (given once, around the wound site) and a series of four vaccine doses on days 0, 3, 7, and 14. For immunocompromised individuals, a fifth dose is added on day 28. Treatment can begin at any point after the bite, as long as the person hasn’t developed symptoms, so don’t assume you’ve “missed the window.” Bites from bats, raccoons, skunks, foxes, and coyotes carry the highest rabies risk in North America. If a dog or cat that bit you can be observed for 10 days and remains healthy, rabies is effectively ruled out.
How to Spot an Infection Developing
Even with proper cleaning, bite wounds can become infected. Watch the wound closely for the first 48 to 72 hours. Signs of infection include increasing redness spreading outward from the wound, swelling that gets worse rather than better, warmth around the bite, throbbing or intensifying pain, pus or cloudy drainage, and fever. One particularly concerning sign is red streaking that extends from the wound up the limb. This is lymphangitis, meaning the infection is spreading through your lymphatic system, and it requires urgent treatment.
Cat bite infections move the fastest. In one case report, a 60-year-old woman developed fever, necrotic tissue at the bite sites, and lymphangitis extending up her entire arm within just one day of being bitten by her own cat. If a cat bite starts getting red and swollen within hours, don’t wait for it to get worse.
The general rule with bite wounds is that they deserve more respect than most cuts or scrapes. The same wound depth from a clean knife is far less dangerous than one made by an animal tooth, because mouths are loaded with bacteria that get deposited deep into tissue. When in doubt, get it evaluated. Early treatment with appropriate antibiotics and proper wound care almost always leads to straightforward healing, while delayed treatment can turn a minor bite into a serious surgical problem.