The hidden dangers of Crocs: They’re the must-have summer shoe for children – but now experts have issued a warning over the silent damage they are wreaking. And its bad news for Birkenstock-loving adults, too…

They’re the polarising rubber clogs surprisingly beloved by everyone from the Princess of Wales to rapper Post Malone.

Once associated more with hospital workers, gardeners and children than the fashion-conscious, Crocs have undergone a remarkable image transformation over the past two decades.

Today, the once-ridiculed clogs have become a Gen Z streetwear staple, worn as readily on city streets as they are in gardens and hospitals.

And in the past few years, they’ve been spotted on the feet of everyone from pop stars to politicians.

When the late David Hockney visited Buckingham Palace in 2022, he wore a checked suit, knitted tie and a pair of lemon-coloured Crocs.

‘Your yellow galoshes,’ said King Charles, himself wearing a pair of polished black brogues, to the artist. ‘Beautifully chosen!’

Housing minister Angela Rayner was photographed in a white pair just last month on her way to Brighton Beach.

And even Kate Middleton is reportedly a fan, having donned hot pink Crocs during a rowing training session on the River Thames back in 2007.

But while the undeniably ugly shoes are now seemingly ubiquitous, experts say Crocs’ comfort may come with a cost.

‘Crocs aren’t inherently bad shoes, but they can cause damage to the feet if worn in the wrong way – or for too long – which many wearers may not realise,’ says Harley Street podiatrist Dr Steven Thomas.

‘This can affect the way you walk, cause aching arches, or blisters. If you’re planning  anything more than a walk on the beach, I would warn against them.’

So what is it about Crocs that are so risky? Made from a foamy material called Croslite, Crocs were first marketed as sailing shoes – named after the scaly creature because the shoes work just as well in water as they do on land.

Croslite is shock-absorbent, easy to clean, soft, durable, slip-resistant and buoyant.

But this material – a proprietary resin derived from a polymer called ethylene-vinyl acetate – can also lead to painful blisters if the shoes are worn for too long, says Dr Thomas.

‘The upside of the rubber-like material is that they’re easy to wash, because they don’t absorb moisture or dirt,’ he explained.

‘But the downside is that this also means that when the foot sweats, there’s nowhere for that sweat to go. It can cause the inside of the shoe to get warm and moist as the sweat accumulates.

‘Moisture increases friction, and this friction increases the chance of blisters.

‘If you’re doing any high-impact activities, where you might sweat, or even in hot weather, wearing Crocs, with or without socks, may not be the best option.’

Conditions such as athlete’s foot, nail fungus and even bacterial infections in small cracks in the skin can also crop up when Crocs are worn for hours, say experts.

Even the way you walk can be affected by wearing Crocs for too long, research shows.

‘Mechanically, wearing Crocs for an extended period – particularly without using the backstrap – can cause you to walk differently,’ says Dr Thomas.

‘Because the shoe isn’t firmly secured to the foot, your toes instinctively curl or grip with each step to stop it slipping off. Over time, that can lead to foot fatigue and subtle changes to your gait.’

As the body compensates, the small muscles and tendons in the feet can become overworked, leading to soreness in the arches and heels.

Foot and ankle surgeon Dr Chandana Halaharvi, of Thrive Foot & Ankle, says repeatedly gripping the shoe can eventually contribute to more serious problems.

‘Crocs have no heel counter or support, so the shoe doesn’t hold your foot – your foot holds the shoe,’ she explained.

‘Do that a few thousand times a day and you are, quite literally, training a deformity.

‘That’s the mechanism behind the hammertoes, claw toes and flexor tendonitis I see in clinic.’

Hammertoes and claw toes develop when the muscles and tendons that control the toes become imbalanced, causing one or more toes to bend into a permanently curled position. 

As the deformity worsens, it can make walking uncomfortable and increase the risk of painful corns and calluses where the toes rub against footwear.

Repeated gripping can also overload the tendons that flex the toes, triggering flexor tendonitis – inflammation that causes pain and tenderness along the underside of the foot.

Experts also warn that the lack of arch support in Crocs may increase the risk of plantar fasciitis, in which the thick band of tissue running from the heel to the toes becomes irritated. 

The condition typically causes a sharp, stabbing pain beneath the heel that is often worst with the first few steps in the morning.

Podiatrist Dr Mike Daniels believes the comfort that has made Crocs so popular may be deceptive.

‘Many people swear they’re the most comfortable shoes they’ve ever worn,’ he said. ‘Classic Crocs have cushioning, but that’s not the same as real support.’

‘I’ve seen some patients with plantar fasciitis feel better in Crocs, while others have developed – or significantly worsened – heel pain after wearing them as their everyday shoes, particularly on hard floors.’

People with flat feet, whose arches naturally provide less support, should be especially cautious, he adds, as they are already at greater risk of developing plantar fasciitis.

And there’s another, more obvious hazard: slipping. The foam soles can provide less traction than conventional trainers or walking shoes, particularly on wet, greasy or polished surfaces, increasing the risk of falls.

‘Studies have shown that Crocs are more slippery than most shoes, and also have a longer slip – meaning the foot travels further before stopping than in other footwear,’ says Dr Thomas.

‘The company took it on board, and they’ve come out with better, non-slip versions as part of their work-style Croc, which is made for use in hospitals and the like.

‘But if you’ve got the generic classic Croc, be wary of slipping – particular if you’re older, or have young children wearing the shoe.’

Despite being one of the most popular summer footwear choices for children, youngsters generally should avoid wearing Crocs any more than occasionally, warns Dr Halaharvi.

‘As a mum, as well as a surgeon, this is something I feel strongly about,’ she said. 

‘Growing feet need a secure heel and proprioceptive feedback to develop normal gait, a shoe children have to grip to keep on is the opposite.

‘Plus, there are well-documented escalator and playground entrapment injuries with soft-clog materials.

‘I also dislike children wearing them during active water play as they easily slip out.’ 

Adds Dr Daniels: ‘Kids loves Crocs and parents love that kids can put them on themselves. But growing feet need time in shoes that actually support normal growth. 

‘Wearing Crocs occasionally to the pool or for short trips is fine. Letting a child live in them from morning to bedtime, especially on hard playground surfaces and concrete, is not what I’d recommend. 

‘I’ve seen kids end up with ankle sprains and toe injuries from tripping over in them as well.’

It’s not all bad news for fans of the clogs, however.

Experts say there’s a simple change anyone can make to vastly improve the foot-friendliness of their Crocs: flip the strap to sport mode.

‘Relaxed mode versus sport mode are functionally two different shoes,’ said Dr Halaharvi.

‘Sport mode secures the rearfoot and stops the toe-gripping. Most people never flip the strap. This is the single most useful thing you can do, however.’

Likewise, says Dr Daniels, stick to wearing your Crocs for short periods.

‘Crocs are not evil shoes. They’re tools,’ he said.

‘The problem is that people try to use them for everything, all day, every day, and then they’re surprised when the foot, ankle or even the knees and back starts hurting.

‘Comfort right now and health over years are not always the same thing. If you spend all day in loose, soft shoes without real support, the plantar fascia and Achilles’ tendon will often pay the price.’

Instead, he says, treat Crocs much like basic flip flops – use them for limited, specific occasions, like for a trip to the beach or pool, yard work, or a quick run into town.

‘They certainly shouldn’t be your uniform for the summer,’ he added.

For longer excursions, says Dr Thomas, maybe try a similarly popular summer sandal: the trendy German-born Birkenstock. 

With adjustable straps, Birkenstocks can be better fitted to the feet, allowing for more support. 

‘They have better arch support, and often come with a backstrap, which gives even more of a snug fit,’ he explained. 

‘Because Crocs are just one unit, you can’t adjust them in this way. But Birkenstocks can give support around the toes, midfoot and back, which makes them a much better option for longer distances.’