There hasn’t been a lot of research on the effects of knuckle cracking, but the limited evidence shows it doesn’t harm your joints.

One review in the Swiss Medical Journal found no evidence in any of the available studies that cracking your knuckles causes arthritis.

A doctor even showed this by experimenting on himself. He reported in Arthritis & Rheumatology that, over a 50-year period, he cracked the knuckles on his left hand two or more times a day but never on his right hand. At the end of the experiment, the knuckles on his left hand were no different than those on his right hand, and neither hand showed signs or symptoms of arthritis.

There’s also no good evidence that cracking your knuckles makes your joints larger or weakens the strength of your grip.

Studies show that as many as 54 percent of people crack their knuckles. They do it for a lot of reasons, including:

  • Sound. Some people like hearing the sound knuckle cracking makes.
  • The way it feels. Some people think cracking their knuckles makes more room in the joint, which relieves tension and increases mobility. However, although it may feel like there’s more room, there’s no evidence that there actually is.
  • Nervousness. Just like wringing your hands or twirling your hair, cracking your knuckles may be a way to occupy your hands when you’re nervous.
  • Stress. Some people who are stressed need to take it out on something. Cracking knuckles may allow for diversion and release without actually causing harm.
  • Habit. Once you start cracking your knuckles for any of these reasons, it’s easy to keep doing it until it happens without even thinking about it. When you find yourself unconsciously cracking your knuckles many times a day, it’s become a habit. People who do it five times a day or more are called habitual knuckle crackers.

The reason the joint makes a popping or cracking sound when pulled is still not completely understood. For a long time, many people attributed the noise to nitrogen bubbles either forming or collapsing in the joint fluid. Others thought it came from movement of the ligaments around the knuckle.

In a 2015 study, researchers watched knuckles while they were cracked using an MRI. They found that a cavity formed due to the negative pressure created when the joint was pulled apart quickly. They determined that the sound was made by formation of the cavity. However, this couldn’t explain the loudness of the sound.

A 2018 study suggested that the sound was actually caused by the partial collapse of the cavity. A review of studies noted that it takes 20 minutes for the cavity to fully collapse so a new cavity could be formed. This may be why after you’ve cracked your knuckles, you’re not able to do it again right away.

Cracking your knuckles shouldn’t be painful, cause swelling, or change the shape of the joint. If any of these things happen, something else is going on.

Although it’s not easy, if you pull hard enough, it’s possible to pull your finger out of the joint or injure the ligaments around the joint.

If you notice your joints are painful or swollen while cracking your knuckles, it’s likely due to an underlying condition, such as arthritis or gout.

Although cracking your knuckles isn’t harming you, it may be distracting to people around you. You might find it difficult to stop if it’s become a habit.

Some tips that might help you break the habit:

  • Think about why you crack your knuckles and address any underlying issues.
  • Find another way to relieve stress, such as deep breathing, exercise, or meditation.
  • Occupy your hands with other stress relievers, such as squeezing a stress ball or rubbing a worry stone.
  • Become aware of each time you crack your knuckles and consciously stop yourself.

Cracking your knuckles doesn’t cause harm, so it shouldn’t be painful, cause swelling, or change the shape of the joint. These are signs that something is wrong, and you should be evaluated by your doctor.

Injuring your finger by pulling very forcefully or moving it in the wrong direction is usually very painful. Your finger may look crooked or start to swell. If this happens, you should see your doctor right away.

If you notice your joints are painful or swollen while cracking your knuckles, it’s likely due to an underlying condition and should be evaluated by your doctor.

According to research, cracking your knuckles isn’t harmful. It doesn’t cause arthritis or make your knuckles larger, but it can be distracting or loud to people around you.

Breaking a habit like cracking your knuckles can be hard, but it can be done. Being aware of when you’re doing it and finding other ways to relieve stress are two things you can do to help you kick the habit.