The possible change in regulations follows news of a Staffordshire mental hospital that permits adults to keep their blades.
In a Bournemouth conference, many nurses said that trying to stop patients from harming themselves makes the situation worse.
In a pilot study at St. George's Hospital in Stafford that will be completed by the end of next year, patients are allowed to have blades and implements. The hospital provides them with cleaning equipment.
Early indications of the study suggest that allowing self-harm can reduce a patient's dependence.
The majority of nurses are in favor allowing adults who cut themselves to continue some forms of self-harm.
Nurses said that around 500,000 people in the UK inflict self-harm, usually as a means of coping with the trauma of previous abuse or problems.
Nurse consultant Chris Holly, who is involved in the Staffordshire pilot, says self-harm can give relief to people who are having suicidal thoughts.
However, Jennifer Clarke-Moore, of the RCN's mental health practice forum, says allowing self-harm is "a cheap-fix solution" to a complicated problem. She advocates instead "evidence-based interventions which promote health."
