Nurses want a change in their professional code to allow them to help patients who self-harm and to be able to do so in hospital.
The Royal College of Nursing is in discussions with the Nursing and Midwifery Council over a change in the nurses' code of conduct.
At present the code says staff must act in the best interests of patients but allowing people to cut themselves could be seen to go against that.
Chris Holley, a consultant nurse involved in a Government-backed pilot study, proposed the debate at the RCN's annual conference in Bournemouth.
She works at South Staffordshire Healthcare NHS Trust, where a six-month pilot is focusing on treatment for adult self-harmers.
At St George's psychiatric hospital in Stafford, some patients can cut or harm themselves in a "safe environment" and have the details put on their care plan.
They are not given fresh blades or instruments to cut with but are allowed to bring in their own. The care plan may state that the instrument has to be kept in a locked drawer and may include details of how often a person harms themselves.
Mrs Holley said there was evidence that other mental health nurses around the UK were overseeing similar arrangements.
She told the conference: "Let me make this point first - this is not about all people who self-harm.
"It is not about handing out cutting implements. It's about people who self-injure in order to manage their feelings and live rather than die."
She said the issue surrounded "a very distinct group" who harmed themselves as a way of coping rather than for attention.
This group often harmed themselves in less visible places such as on their belly, she said.
By allowing them to self-harm in hospital, the feelings of being criticised or judged over their behaviour were reduced, she said.
Meanwhile, the mental health team worked on the underlying problem, such as difficulties expressing emotion or abuse in childhood.
Mrs Holley said there were early indications from the pilot to suggest that the approach was reducing the incidence of self-harming.
About 500,000 people around the UK are thought to self-harm.
The most common methods involve cutting, burning, scalding, banging or scratching the body, breaking bones, pulling hair or swallowing toxic substances.
Treatment focuses on coming up with alternative ways of dealing with problems and underlying causes.
Mrs Holley acknowledged the issue was controversial but said it was important for nurses to put their "heads above the parapet".
Ian Hulatt, mental health adviser to the RCN, said self-harming related to when a person felt "de-personalised".
He added: "It's a coping mechanism that works but like many coping mechanisms, it's potentially harmful."
The RCN is currently in discussions with the Nursing and Midwifery Council about a possible review of the code.
Mr Hulatt said such "therapeutic risk taking" in mental health was becoming increasingly the norm.