Health
The Truth About Cracking Your Knuckles Habit
Health Points
- Cracking your knuckles is generally harmless and doesn’t cause arthritis.
- The popping sound comes from gas bubbles bursting in your joint fluid.
- Forceful joint cracking or cracking other joints, like the neck, can be risky.
For many, cracking knuckles is a small daily ritual that can bring a sense of instant relief. It might be an irresistible habit, a quirky comfort, or even an occasional distraction when boredom strikes at work.
But despite how common it is, this familiar “pop” has long been surrounded by myths. Maybe you’ve been warned that it leads to arthritis or causes fingers to swell and deform, or perhaps hoped it keeps joints limber with regular practice.
To set the record straight, Dr. Natalie Azar, rheumatologist at NYU Langone Health, shared insight into what really happens when you crack your knuckles and if there’s any impact on your joint health.
When you “crack” your knuckles, you’re manipulating the finger joints—medically known as the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints. Bend your fingers in a certain way, and you’ll feel or hear the familiar snap.
“Research shows that the cracking sound is from gas bubbles in the joint bursting or collapsing,” Dr. Azar explains. These mini bubbles form inside the synovial fluid that lubricates joints. When you stretch or bend a finger, you create more space inside the joint—and the gas bubbles burst, creating that signature noise.
Some people can crack certain joints more easily than others. “It’s likely related to differences in anatomy, the mechanics of the joint movement, as well as the characteristics of the joint fluid,” notes Azar. Simply put, some joints have more synovial fluid or flexibility, making them more prone to popping.
However, you should never force your joints to crack. If it isn’t happening naturally, let it go.
So, is all that cracking bad for you? The good news: current evidence shows knuckle cracking is generally harmless for most people. “Regular knuckle-cracking won’t cause the finger joints to become larger or more prominent,” according to the Cleveland Clinic. The risk comes only if you apply excessive force. Overzealous knuckle-crackers may sometimes injure tendons, ligaments, or even cause dislocations. If you notice pain, stiffness, or swelling after trying to crack a joint, it’s time to call your doctor.
Worried it will lead to arthritis? Decades of studies—including an unusual “self-experiment” by Dr. Donald Unger, who cracked the knuckles on only one hand daily for 50 years—show no evidence of a connection. After half a lifetime, Dr. Unger found no difference in the two hands and published his findings in the journal Arthritis & Rheumatology.
Are there benefits to seeking out that satisfying snap? Not really, says Dr. Azar. “It can maybe be a stress reliever.” Any brief feeling of refreshment or flexibility after a crack is likely fleeting, but if it soothes you mentally, that may be a small plus.
While cracking knuckles is safe for most, there are some important cautions. Some joints—like those in the neck or back—are structured differently and far more delicate. Unsupervised or forceful cracking movements in these areas can be dangerous, increasing risks of nerve injury, damaged blood vessels, or even blood clots. Always talk to a healthcare professional before attempting any at-home joint manipulation outside of your fingers.
If you experience new pain, swelling, or sudden changes in finger motion after cracking your knuckles, check in with your doctor. Otherwise, for most adults, an occasional finger-pop is nothing to worry about—so you can snap away, guilt-free.
