Many nurses believe the NHS has a culture that discourages staff from raising concerns about patient care, a survey suggests.
Almost 30% of 800 nurses in the UK polled by Nursing Times magazine said being seen as a troublemaker was the biggest barrier to them speaking out.
Inaction by managers was cited as a barrier by 23%.
The government said it had taken measures to support whistle-blowers and was considering further action.
The survey was sent out to the magazine’s database of nurses and conducted online.
Some 84% of respondents to the poll said they had raised concerns about a colleague’s practice or attitude.
A total of 23% of the nurses said they had done so “several times” or “regularly”, and 23% “at least once”.
But of those who had raised concerns, 52% said there had been no appropriate outcome after they had spoken out and a similar percentage said they had faced negative consequences as a result of doing so.