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Is cracking your knuckles bad for you?

In partnership with Dr Hamish Black

What happens when you crack your knuckles?

Middle-aged man with a beard wearing a red beanie and t-shirt cracking his knuckles
Middle-aged man with a beard wearing a red beanie and t-shirt cracking his knuckles

Just like pineapple on pizza or the taste of coriander – for most, you either love cracking your knuckles, or despise the very sound of it.

But love it or hate it, when it comes to the crunch, does cracking your knuckles cause you any harm?

What happens when you crack your knuckles?

Before we find out if knuckle cracking is harmful, what exactly is that cracking or ‘popping’ sound that we hear when someone cracks their knuckles?

For something that’s such a common habit, nib Group Medical Advisor Dr Hamish Black says there’s actually some uncertainty about what makes that sound. “I don’t think anybody knows for sure,” he says.

He notes that most theories relate to the fluid, known as synovial fluid, which sits between the joints in your fingers (and other parts of your body). This fluid provides a natural lubricant to help your body’s joints move smoothly.

When the fingers are stretched and the joints forced apart, it causes gas bubbles in the fluid to collapse or burst. This is believed to make the ‘popping’ sound.  

This is also thought to be the reason why you can’t re-crack your knuckles immediately after cracking; it takes time for the gas bubbles to build up again.

Does it actually do any harm?

If you like to crack your knuckles, you may have been told that you are at risk of damaging your joints, or even getting arthritis.

Fear not. Hamish says knuckle cracking is not likely to cause you harm. And studies have specifically found there is no definite link between cracking knuckles and arthritis.

Studies have found there's no definite link between cracking knuckles and arthritis

However, Hamish notes that knuckle cracking may be harmful for people with certain joint disorders.

“For example, if you had an underlying hypermobile joint syndrome – where your joints move beyond the normal range of motion – you could damage the ligaments from the stress of pulling.”

That said, if you start to feel pain when you crack your knuckles, he recommends you see a health professional to find out what is causing the discomfort.

Why do people feel the urge to crack their knuckles?

Hamish says when people self-manipulate or ‘crack’ parts of their bodies – including their neck, back or wrists – they may feel less stiff or like they have increased mobility. The feeling is both physical and psychological.

“There is a placebo effect of feeling like something has happened to ‘cure’ you or ‘get the joint back in line’,” he says.

“Studies have shown that patients have less pain and better function after having a crack from spinal mobilisation, even if that crack occurred at a level well away from where the injury or back pain is.”

Cracking joints may give you that feeling of tension release that you get when you stand up and give your body a good stretch after a sitting for a long time.

What can I do instead?

While knuckle cracking is generally harmless, some see it as a habit that they want to break (if not for them, for those around them who get annoyed by it).

Like any habit, the first thing you can do is try to identify what causes you to crack your knuckles. Is it in response to a certain stress? Or boredom?

Once you know the triggers, you can start to change things up and think about some new healthy (and perhaps quieter) habits to replace your knuckle cracking.

Please note: The tips throughout this article serve as broad information and should not replace any advice you have been given by your medical practitioner. 

Dr Hamish Black

Dr Hamish Black

In partnership with

Dr Hamish Black

Dr Hamish Black has been a medical practitioner for more than 25 years. In addition to his role as nib group medical advisor, he still spends two days a week practising as a GP. He has spent many years working in emergency departments and in rural Australia, including a stint with the Royal Flying Doctor Service. Hamish also loves karaoke and dancing (though not that well at either, he says!), with Play that Funky Music by Wild Cherry being his karaoke favourite.