Is cracking your knuckles bad for you?
No — cracking your knuckles does not cause arthritis. Studies have found no link. Here's what's actually happening when you crack them and what the science says.
2 min read · Updated 2026-04-14
For informational purposes only. This content is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making health decisions.
Short answer
No, cracking your knuckles does not cause arthritis. Multiple studies have found no link between knuckle cracking and arthritis or joint damage. The sound is caused by gas bubbles in the synovial fluid popping — not bones grinding. It's mostly harmless.
What actually happens when you crack your knuckles
Your joints are surrounded by synovial fluid — a lubricating liquid that reduces friction. This fluid contains dissolved gases (oxygen, nitrogen, CO2).
When you pull or bend a finger joint:
- The joint space rapidly widens
- Pressure drops inside the joint
- Dissolved gases form a bubble
- The bubble collapses — making the "pop" sound
After cracking, it takes about 20 minutes for the gases to dissolve back into the fluid, which is why you can't crack the same joint immediately after.
What the studies say
The most famous study: Dr. Donald Unger cracked the knuckles on only his left hand every day for 60 years and kept his right hand as a control. After 60 years, no arthritis in either hand. He won an Ig Nobel Prize for the research.
Larger studies: A 1990 study of 300 knuckle crackers found no correlation with arthritis. Research has found slightly higher rates of hand swelling in frequent crackers but no consistent findings on arthritis.
Is there any downside?
Possibly, for extreme habitual crackers:
- Some research suggests reduced grip strength over many decades
- May cause minor irritation to surrounding tissues over time
- Annoying to people around you (social cost, not medical)
But occasional knuckle cracking? No credible evidence of harm.
Why the myth persists
Parents told children it caused arthritis for generations — it's one of those health myths that gets passed down without evidence. The cracking sound sounds alarming, which makes people assume damage is occurring.