The UK government is imposing stricter regulations on the sale of laxatives, to help prevent their misuse.
The drugs, designed to treat constipation, will be sold in smaller packs that carry warnings about never using laxatives for weight control.
People will need to be 18 or older to buy them from pharmacies and supermarkets.
Rebecca Wojturska, who has overused the drugs in the past, welcomed the safeguards.
The 30-year-old, from Fife, said although eating disorders did not discriminate by age, many sufferers were younger than 18.
“It is a really good idea to stop selling them to people younger than 18,” she said.
“It’s another barrier that could help.”
The eating disorders charity Beat said its own research had found many sufferers who abused laxatives had bought them over the counter.
Parents and carers will still be able to buy stimulant laxatives for short-term use in children aged 12 and over.
But they should seek advice from a prescriber such as their GP if the child is younger than 12 or they are worried about their child’s health, the Medicines and Healthcare products Regulatory Agency (MHRA) says.
Laxatives are safe drugs when used as recommended – but overuse can cause diarrhoea, dehydration and imbalances that can lead to kidney failure.
And anyone with regular bouts of constipation is advised against the long-term use of stimulant laxatives – including products containing bisacodyl, senna or sodium picosulfate – which can result in damage to the digestive system, including chronic constipation and damage to the nerves and muscles of the colon.
Dr Sarah Branch, from the MHRA, said: “Stimulant laxatives can provide short-term relief to some people with occasional constipation.
“And most people use these medicines safely.
“However, there is evidence of misuse by people with eating disorders, and of long-term use by the elderly, as well as inappropriate use in children.
“Patient safety is our highest priority.
“We believe these new measures are necessary to address the risks associated with misuse, while continuing to allow safe and appropriate access to these medicines without prescription to treat short-term constipation.”
If you’ve been affected by eating disorders, help and support is available via the BBC Action Line.
Products available for general sale (in shops and supermarkets) will be limited to a pack size equivalent to two short treatment courses (up to 20 standard-strength tablets, 10 maximum-strength tablets or 100ml solution/syrup). This limit is to reflect that these medicines should be used for only short-term, occasional constipation.
Pharmacies will continue to hold larger packs of up to 100 tablets for use in adults and children aged 12 years or older, under the supervision of a pharmacist.