Most people who regularly take epsom salts baths – including the queen of wellness herself, Gwyneth Paltrow – will tell you that it's one of the most enjoyable ways to de-stress after a long day.
Equally, many others still only really associate them with marathon runners and the elderly.
Either way, people are increasingly incorporating epsom salt soaking into their bedtime routine, claiming it helps them to unwind and get a better night's sleep.
Paltrow once told Elle that epsom salts make up one of the "most low key" elements of her bedtime ritual: "I take a bath every night in regular epsom salts from the drug store Dr. Teal's, which is great for skin and purity of skin and relaxation to get all the energy of the day off," she told the magazine.
And according to Pinterest, there's been a 105 per cent increase in searches for epsom salts on the platform since January.
What are epsom salts?
Epsom salts are mineral compounds that break down into magnesium sulfate in water. They were first discovered around 400 years ago at a natural spring in Epsom, Surrey, Jim Hill, president of the Epsom Salt Council told the Standard. They have been ingested as a laxative and soaked in for healing and soothing purposes ever since.
What are the benefits of soaking in them?
Many people say that taking a bath in epsom salts leaves their skin feeling silky, smooth, even detoxified. Hill told the Standard that despite the name, it doesn't contain any sodium chloride, which can have a drying effect or make you feel sticky afterwards, and will instead leave you feeling "moisturised."
Magnesium is "the forgotten mineral," Hill said, adding that it plays an important role in relaxing the body, relieving tension, and calming nerve endings in muscles, hence why many people swear by bathing in epsom salts to relieve cramp or aches and pains after intense exercise. It can also help to regulate the activity of some enzymes, he said.
There is scepticism, however, in the scientific community over whether or not your body is capable of absorbing these minerals through the skin.
In 2016, though, professors from the University of Birmingham conducted a review into the absorption of epsom salts across the skin and concluded that bathing in epsom salts in fact can increase sulfate and magnesium levels in the body.
Dr Rosemary Waring, one of the authors of the study, told the Standard that there is significant German and Russian literature to back this up.
There are many claims that celebrities, influencers and regular people have made about the benefits of using epsom salts, including that they can help to relieve anxiety, migraines, reduce inflammation and soothe skin conditions, though many of these are purely anecdotal.
"Some people also believe epsom salts help to redistribute water, but we don’t know for sure," Hill said.
Celebrity trainer James Duigan, whose famous clients include the likes of Elle Macpherson, revealed in his 2011 book Clean & Lean Diet: Flat Tummy Fast that he always recommends his clients soak in an epsom bath before a shoot or holiday, to help "shed toxins" and avoid water retention, according to Body and Soul.
While there's a lack of scientific proof to back that up, it's an interesting insight into the beauty secrets of supermodels.
There are beauty uses for epsom salts, too. The Epsom Salt Council recommends using them as a natural exfoliant, or combining half a teaspoon with your cleanser for a deep-pore facial scrub.
Hill says they can even be used as a hair volumiser. The council's advice is to mix equal parts warm conditioner and epsom salts, then work the mixture into your hair and leave for 20 minutes before rinsing – and we'll definitely be trying that one.
So how much should we be using and how often?
Hill advises adding two cups to your bath "to really feel the full effects."
"Our definition is as needed," he told the Standard. "Always after heavy exercise. If I really need to sleep before a presentation the next day or if I've had a particularly stressful day [I'll take one]. I know people who take them every day, once a week and even less often, but most of the users I come across have some sort of regiment."
"It’s not a cure all," Hill went on. "It’s not going to fix you, what we're saying is that [epsom salts] are going to help with a lot of things, improve your performance and, to put the cherry on top, it’s inexpensive. You can get all these benefits for the price of a cup of coffee, so it’s struck a chord with different generations."
The council's line of advice to people purchasing epsom salts is to always look for a BP designation on the label – which will tell you it was produced in accordance with pharmaceutical standards.