The freedoms give everyone aged 55-plus flexibility on how to use their defined contribution pension funds.
However, nearly two out of three (64%) over-55s said they are confused by the regulations and the overwhelming majority (82%) said they want an end to any further government changes to pension rules.
More than one in three (42%) said they are concerned about running out of money during retirement, while 41% worry about paying for long-term care.
The research, however, also showed that the freedoms have had some positive impact in encouraging people to save and plan for their retirement.
Since the rules came into effect, 11% of over-55s who are still in work said they had started saving into a pension for the first time, encouraged their partner to save more, increased pension contributions or restarted pension saving.
One in seven (14%) are also making a greater effort to learn about retirement savings.
Vince Smith-Hughes, a retirement income expert at Prudential, said: “The reality of pension freedoms is hitting home as consumers begin to understand that they are responsible for ensuring they have enough money to last throughout their retirement.
“The fear that they might run out of money is forcing them to take a long, hard look at how much they should be saving to ensure they have the retirement they want,” he said.
Smith-Hughes added: “The fact that many over-55s are preparing to work longer and save more highlights that they recognise this risk and are responding in a rational and responsible way.”
The online survey was conducted by Consumer Intelligence for Prudential between 23 and 25 February 2018 among 1,000 UK adults aged 55+ and included those who are working and retired.