Diseases & Conditions
Human bites, while often overshadowed by animal bites, are surprisingly common and carry a high risk for infection. Often affecting the hand, human bites deposit large amounts of bacteria into the wound. In fact, up to one-third of all hand infections are caused by human bites.
Even when human bites are small and appear relatively harmless, they can cause severe infections involving skin, tendon, bones, and joints. If not treated quickly, these infections can worsen quickly and cause major complications, including destruction of joints and tendons.
Human bites may occur directly when one person bites another person (e.g., a child biting another child).
However, human bite wounds are often caused indirectly during fistfights when a person's closed fist strikes the tooth of their opponent during a punch, breaking the skin on the hand.
A punch to the mouth can result in an indirect bite injury at the knuckle joint (metacarpophalangeal joint) where the tooth enters the joint. This drives countless bacteria into the joint, which can cause a severe infection known as “fight bite.” These infections usually occur a few days after the incident. They are typically aggressive and can damage the joint, requiring:
- Surgery in the emergency room or operating room to clean out the infection
- Treatment with antibiotics
When human bites do not break the skin, they may not cause an infection; however, the crushing force of the bite may still damage structures under the skin, such as tendons, nerves, and bones.
Damage to tendons, nerves, bones, joints, and other structures can result in a variety of issues, including but not limited to:
- Deformity (crookedness)
- Reduced function (e.g., the inability to move an affected finger)
If the skin is broken, there is a real possibility of infection in addition to injury of the structures mentioned above. Infections can occur soon after the injury (hours to days) and may spread rapidly.
Signs of an Infection
- Drainage from the wound
- Warmth around the bite wound
Signs of Tendon or Nerve Damage
- An inability to bend or straighten the affected finger
- Deformity (crookedness) of the affected finger
- Pain with attempts to move the affected finger
- A loss of sensation over the tip of the affected finger
Your doctor will likely ask how the bite happened. Be prepared to tell your doctor how you got the bite. If the bite occurred during a fight, your doctor may be more concerned that the injury penetrated (entered into) your hand knuckle joint (metacarpophalangeal joint), requiring prompt treatment.
During your exam, the doctor may:
- Measure the wound, note its location, and check for signs of damage to the nerves, tendons, bones, or other structures
- Test your ability to move your fingers and test the feeling at the tip of your fingers
- Examine your arm for red lines, swelling, pain, and other signs of a spreading infection
- Order X-rays to look for fractures and blood tests to look for infection
- Give you a tetanus shot and/or prescribe antibiotics
If the doctor suspects that bones, joints, tendons, or nerves have been injured, you may need to see a specialist for additional treatment. Surgery may be necessary if you have a severe injury to one of these important structures and/or if you are developing an infection.
Initial treatment includes stopping bleeding and cleaning out the wound.
As mentioned above, infection is one of the biggest concerns following human bites, and treatment will focus on preventing or treating infection. This may include:
- Taking antibiotics
- Ensuring your tetanus vaccine is up to date, and getting a booster if it is not
In addition to common bacterial infections, human bites can transmit other diseases from one person to another. These may include:
- The human immunodeficiency virus (HIV)
- The hepatitis B and C viruses
If transmission of one of these diseases is a concern, your doctor may prescribe medication to prevent the disease from occurring. Time to treatment matters, and it is very important to seek medical care following a human bite.
- Stop bleeding by putting pressure on the bitten area with a clean cloth or sterile gauze.
- Do not put the bitten area in your mouth. This adds bacteria into the wound, which can lead to infection.
- Wash the wound thoroughly. Use soap and water or, if it is available, sterile saline.
- Pat the wound dry and apply a sterile bandage.
- Inspect the area carefully. If the fingers cannot be straightened or bent or if there is numbness, you may have tendon, bone, or nerve damage; you should seek prompt medical care.
- Even if the wound appears small and harmless, if the skin is broken, you should seek medical care promptly. The tooth may have penetrated deeper than it seems, resulting in a high chance of infection.
- If the skin is not broken, keep a close eye on the injury and seek prompt medical attention if you develop concerns, such as signs of infection.
- Stop bleeding by applying pressure to the bite area with a clean cloth or sterile gauze.
- Once bleeding has stopped, wash the wound thoroughly. Use soap and water or, if it is available, sterile saline.
- Pat the wound dry and apply a sterile bandage.
- If bleeding continues, continue to apply pressure, and elevate the body part that has been bitten.
To prevent complications from a deep wound, get medical attention within 24 hours of being bitten — or sooner, if possible. Urgent surgery may be needed for a suspected joint or tendon infection.
Outcomes for human bites vary depending on the seriousness of the injury and promptness of medical attention.
- Nerve injuries can be repaired, though nerves rarely recover completely even with optimal treatment, so you may have less feeling in the hand or finger that was bitten than you did before the injury. However, it is important to note that repairs done soon after an injury tend to do better than repairs done several weeks after the injury.
- Untreated fractures and tendon injuries can result in deformity (e.g., a crooked finger) and dysfunction (e.g., inability to bend or straighten the finger). However, bone and tendon injuries that are treated quickly and appropriately can have good results.
- Untreated joint infections (e.g., “fight bite”) can be devastating and result in permanent loss of joint function (a painful and stiff finger). However, infections that are treated quickly can have good outcomes.
Thus, it is very important to seek medical attention soon after a human bite to ensure the best result from your treatment.
Contributed and/or Updated by
AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.