Demand for weight loss drugs is becoming so “unsustainable” that demand may soon outstrip supply, pharmacists have warned.

The National Pharmacy Association (NPA) said supply problems could encourage people to turn to unregulated online sources, despite the risks involved.

The number of people in the UK using drugs such as Wegovy and Mounjaro has soared to well above a million, with most patients paying to get them privately.

During April, 1.6m packs of Mounjaro and Wegovy were bought in Britain, with the number thought to correlate closely with the number of people using them.

“Spiralling demand for weight loss medication risks going far beyond what is clinically deliverable”, the NPA said.

The drugs might need to be reserved for those in greatest need because they are so overweight instead of being given to the “worried well”, it added.

New polling has found that 21% of Britons have tried to get hold of the medications over the past year, a figure that rises to 35% among 18- to 34-year-olds.

The same survey found that 41% of all age groups would use them if they were free on the NHS. This figure rose to 64% among those aged 25-34.

Savanta interviewed a representative sample of 2,002 adults aged 18 or over online from 20-23 June for the NPA, which represents 6,000 independent pharmacies.

“Weight loss jabs are one of the biggest drug innovations this century but growing demand for weight loss treatment highlights the need to make sure this is appropriate for those who want it,” said Olivier Picard, the NPA’s chair.

“It’s clear from this polling that more people are interested in getting weight loss jabs than can benefit from weight loss medication.”

Supply of the medicines has been hit by shortages in some parts of the UK, including for higher doses of Mounjaro, the NPA said. Supply has been restricted to some pharmacies, which has stopped some new patients from going on to the drugs.

The Medicines and Healthcare products Regulatory Agency, the UK’s drugs watchdog, has warned patients to obtain the drugs only with a doctor’s prescription, and not from beauty parlours or websites.

A Department of Health spokesperson said more people would be able to obtain “revolutionary” weight loss jabs over the next few years.

“Weight loss drugs are a powerful tool in tackling the obesity crisis head-on as part of our 10-year health plan”, they added.

“This government is committed to ensuring that more people have access to these revolutionary drugs when needed, and crucially that they are able to do so in a safe and controlled way. We will ensure that those most in need will receive treatment first.”

About 220,000 people in England are due to be offered tirzepatide, a diabetes drug that promotes weight loss, over the next three years.

Pharmacies already provide about 85% of all weight loss drugs and need to be closely involved in the expansion of access, Picard added.

“The government should use the massive untapped expertise and skills of pharmacists to help speed up the NHS’s weight loss medication programme to millions of the most in need patients,” he said.