"Short-sighted" plans to scrap bursaries for nursing and midwifery will have a "detrimental effect on the NHS workforce", according to leading health unions, patient organisations and royal colleges.
This in turn could have an impact on patient care and safety, they warned.
In an open letter to the Prime Minister, leaders from across the health sector said they were deeply concerned about plans to replace bursaries with loans for those studying nursing, midwifery and other health degrees.
The Government has said that replacing bursaries with loans will free up around £800 million a year, create extra nursing posts by 2020 and help students from all backgrounds take up the role.
But the coalition of health leaders, including those from the Royal College of Nursing, the National Union of Students, the Royal College of Midwives, Unison and Unite, have implored the Government to halt its plans and consider the implications on patient care in England.
The letter says: "These plans are a short-sighted attempt to solve a long-term and complicated problem.
"They have not been properly risk-assessed, and continuing with them as they stand would be nothing short of reckless."
It adds that the proposals are "an untested gamble with the future of the workforce" and "have not been properly risk assessed".
"These proposals will have a detrimental effect on the current and future NHS workforce, and also on the quality of patient care and safety provided in England."
The group urged David Cameron to reconsider the plans and called for a meeting to discuss their concerns.
A Department of Health spokesman said: "We need more home-grown nurses in the NHS because they do an amazing job caring for patients, but currently two-thirds of people who apply to become a nurse aren't accepted for training.
"Our plans mean up to 10,000 more training places by the end of this parliament, with student nurses getting around 25% more financial support whilst they study."