The NHS in London spent almost £13m on public relations in the last three years, a BBC London investigation has found - enough to recruit 600 nurses.
Some £9.7m went on press officers' salaries at hospitals and primary care trusts (PCTs), while private PR companies were paid a further £3m.
Critics called for "medical doctors not spin doctors", pointing to longer waiting times and cancelled operations.
Some trusts said PR spending was needed to educate the public on health issues.
The BBC sent Freedom of Information requests to all 33 London hospitals, in addition to the capital's primary care trusts and NHS London.
The research revealed some 82 press officers on the public payroll, with an average salary of £37,278.
By contrast, in 1981 there were only eight press officers working in the entire NHS.
Katherine Murphy, chief executive of The Patients Association, said: "Far too many patients experience longer waiting times, cancelled operations and standards of care below what they deserve.
"These figures are a concerning example of the cost of NHS PR - it is sadly patients paying the price.
"Many will ask whether this funding would be better spent on medical doctors, rather than spin doctors."
Yet the outlay on staff press officers was supplemented by millions of pounds handed to private PR firms.
NHS North West London handed PR firm the London Communications Agency almost £1m for "communications and engagement work" on a consultation programme.
The organisation said the value of the consultation was "incalculable".
And Tower Hamlets PCT paid four different PR companies a total of £353,391 over the three-year period.
The organisation insisted much of the spend was on public health campaigns with real value.
Many smaller spends on private PR firms were dubbed wasteful by critics too.
Chelsea Children's Hospital paid Eureka Marketing Solutions £10,620 to design a logo and "branded merchandise".
Defending the outlay, a spokeswoman said patients "relate to" the branding which "helps create an environment where they felt safe and comfortable".
Meanwhile the Royal Free Hospital Hampstead paid a PR company £12,427 for advice on handling the UK's first face transplant.
This was despite employing five press officers of its own - with a total wage bill of about £198,000.
Dr John Lister, of pressure group London Health Emergency, said: "I find it hard to explain this sort of spending.
"Sadly the default setting of NHS managers seems to be bringing in private consultants to do jobs staff should be doing.
"It's alarming - most people would regard it a total waste of money."
A Royal Free spokeswoman said a 2011 survey showed its communications team was "particularly good value for money".
She insisted: "From time to time it's necessary to use specialist public relations services, particularly when an issue threatens to overwhelm the existing resources, as during the high-profile face transplant story.
"The trust considers it received very good value for money from the company."
Meanwhile the Royal Marsden Hospital paid a firm £1,500 - to "print news clippings following the visit by the Duke and Duchess of Cambridge".
The Jonathan Street agency based in Mayfair has bagged at least 36 contracts with hospitals and primary care trusts in the city in the last three years.
The BBC has been able to trace at least £634,011 in NHS payments to the firm in that time and it is currently hired by 11 London hospitals.
Director Mark Purcell admitted the workload was carried out by him alone since the death of founder Jonathan Street.
But Mr Purcell said: "We haven't been involved in the big money PR work - and we like to think we offer a good service to people we have dealt with.
"Our reputation stands on what we've done in the past."
Much of the firm's work is handling NHS press operations on weekends, and Mr Purcell said: "Saturday and Sunday can be busy times, but it varies. We do get quiet days."
A Department of Health spokesman said: "NHS organisations are responsible for how they spend their funds, including their responsibility to communicate with patients and the public.
"However, we are clear the NHS must focus on improving the quality of care for patients.
"Money should only be spent on external consultancies if this is absolutely necessary and provides good value for money."
'Keeping Londoners happy'
The Chartered Institute of Public Relations defended the use of PR firms by the NHS.
Chief executive Jane Wilson said: "NHS public relations professionals work directly with health care professionals to ensure issues such as wellness and healthy living campaigns are properly communicated.
"These campaigns aim to save the amount of time and public money spent on public health issues which can prevented at source by information provision and the raising of awareness.
"In doing so, they help keep Londoners healthy and happy."