Women having breast implants should be warned about a condition linked to chronic pain and extreme fatigue, the British Association of Aesthetic Plastic Surgeons (BAAPS) has said.
Tens of thousands of women on online forums claim they have suffered breast implant illness (BII), of which there is little scientific evidence.
Surgeons, including from BAAPS, are now calling for more research.
The regulator said it monitored issues and would act where appropriate.
Breast implant illness is not an official diagnosis, but some women who believe they have it say they returned to full health after having their implants removed.
The MHRA says there have been more than a million breast implant operations in the UK, and surgeons say most patients are happy with the results.
But a number of women told the Victoria Derbyshire programme they experienced complications which they had not been warned about.
Fitness instructor Naomi Macarthur, 28, decided to get breast implants in 2014, but within weeks she said she began to suffer “the most horrific symptoms”.
“I remember getting severe pain in my stomach,” she said. “And the tiredness was like I had run a marathon and dug a million trenches and I hadn’t done anything. Writing with a pen was too tiring.”
As time went on she experienced a long list of symptoms including hair loss, allergies and rashes.
“It’s been absolutely horrific,” she said, breaking into tears.
Ms Macarthur, who is from Brighton, said doctors repeatedly told her the illness was unrelated to the implants, and at one stage diagnosed her with lupus.
Then, last year, she discovered breast implant illness and found online support groups.
She decided to have her implants removed, and said within days the symptoms which had affected her life for four years began to disappear.
“I can’t believe how amazing I feel, and how I have bounced back,” she explained. “It’s insane.”
‘Very real for them’
In parts of the medical community there remains scepticism towards breast implant illness.
The BBC spoke to one surgeon – who did not wish to be named – who said he did not believe it was a real condition.