Menstrual cups fit into the vagina and collect period blood but are not currently regulated in the UK, and there is no safety testing. Incorrect use of menstrual cups could be resulting in some women suffering pelvic organ prolapse
Menstrual cups, which can last up to 10 years, have grown in popularity as a more sustainable alternative to single-use tampons and pads
But there are claims that more education is needed before women decide to use them.
The Chartered Society of Physiotherapy wants some manufacturers to include better safety advice. The government said the NHS was improving pelvic health clinic access.
One woman, Jenny, told the BBC’s Victoria Derbyshire programme she believed menstrual cups were responsible for her minor pelvic organ prolapse, after she had used them for three months.
“I was scared and I was worried,” she said. “I didn’t know what it might mean in the long term.”
Pelvic organ prolapse occurs when the group of muscles and tissues that normally support the pelvic organs, called the pelvic floor, becomes weakened and cannot hold the organs in place firmly.
It causes one or more of the organs to drop down from the normal position and bulge into the vagina. This can be the womb, bowel, bladder or top of the vagina.
Symptoms can usually be improved with pelvic floor exercises and lifestyle changes, but sometimes medical treatment is needed.
“There was no warning to say… this was a possible side-effect,” Jenny explained.
“And I had really thoroughly read the instructions, so I thought I was doing everything properly.”
The vast majority of women do not encounter any problems.
There is limited research on the products, but in a report by the Lancet Public Health journal last year – which looked at 43 studies involving 3,300 women and girls living in rich and poor countries – the authors concluded menstrual cups were a “safe option”.
But the Chartered Society of Physiotherapy is calling for the cups – which are produced by a growing number of manufacturers worldwide – to be better regulated.
Currently they are not safety-tested, and there is no industry standard or body responsible for collating complaints.
Physiotherapist Kate Lough told the BBC: “Having looked at some of the information on some of the cups – particularly the information about taking the cup out -[it] is not correct and is hard to understand,” she said.
“Using your pelvic floor muscles to bring the cup lower in the vagina is not correct.”
She added: “Bearing down on the cup to push it within reach of your fingers is not good pelvic floor advice. (BBC Health)