Community pharmacies could close at the rate of more than one a day if proposals for deregulation go ahead, warn analysts.
Community pharmacies are under threat
Current rules limit licences for pharmacies to those that will provide a "necessary or desirable" service in a given local area.
However, a proposed liberalisation of this rule would enable large out-of-town supermarkets to muscle in on the sector, providing their staff are properly trained.
A report by the New Economics Foundation argues the potential impact on community pharmacies could be devastating and undermine the government's own stated aim of developing their role to provide more front line health services.
A typical community pharmacist
Gives free advice 2,500 times per month
On average serves 50 diabetics, 150 asthmatics, 500 people with high blood pressure and 20 cancer patients
Deregulation would also raise the spectre of patients being forced to carry out sensitive transactions in a large, busy and impersonal environment.
In addition, the report warns that the people who are most dependent on pharmacies - the elderly, chronically ill, disabled and disadvantaged - are also those least able to access a remote retailer.
The report predicts that over 6,000 community pharmacies could be under threat from supermarkets.
About 4% a year - or more than one a day - would close.
The National Pharmaceutical Association argues that the range and choice available in the current pharmacy network will be lost as pharmacies cluster around GP surgeries and profitable urban centres to survive.
This will leave rural or deprived areas as potential "healthcare deserts", says the New Economics Foundation.
Andrew Simms, NEF policy director, said: "The health of Britain's local economies are already under threat from economic forces that are out of control.
"If the government follows the OFT's proposals it will be a self-inflicted wound on their vision of a larger role for community pharmacies.
"Handing pharmacies over to supermarkets would bring on a double coronary in local communities, undermining frontline health services and further attacking the economic viability of the UK's high streets."
A survey for the Patients' Association suggests almost three quarters of the public fear their high street pharmacy will close if even more supermarkets dispense prescriptions.
But major retailers Asda and Tesco insist deregulation will lead to more choice for consumers.
Ministers are due to respond to the OFT proposals in the Spring.