A similar scheme in the Netherlands led to a surge in costs as the number of users jumped 10-fold within eight years, according to European public health experts. There were also 'credible reports of fraud' among users, they said.
England must learn from the Dutch system to avoid similar problems, they wrote in a BMJ analysis.
Personal health budgets, which give patients control of a budget to purchase the type of care they want to receive, are being piloted in 64 PCTs ahead of planned roll-out in April 2014.
Health secretary Andrew Lansley has said this will give patients more control over the care and support they get.
But a similar scheme in the Netherlands has been branded 'unsustainable' by the country's Ministry of Health, researchers said.
They wrote: 'If the English proposals are to succeed they will have to establish clear rules and regulations, along with adequate support to enable people to administer their budgets independently, without specialised private agencies," say the authors.
Researchers continue: 'The UK government must also recognise that personal budgets can create new demand.
'Consequently, eligibility rules and entitlements should be evaluated carefully to avoid creating false expectations and potentially disappointing many people'.
The Dutch system, introduced in 1997, led to a 10-fold increase in the number of budget holders in 2002-10, from 13,000 to 130,000. Spending on the scheme rose 23% per year, from €400m to €2.2bn in this time.
Concerns were raised by the growth of companies that broker arrangements between clients and providers, they wrote.
These and other concerns have led to large-scale reorganisation of the Dutch system, including restricting access to only those who would have otherwise entered a care home.
Warning about England's plans, the experts said: 'Unless the lessons of the Dutch experience are learnt, the unintended and negative consequences will outnumber the positive, empowering role of personal budgets.'