The three Royal Colleges representing physicians across the UK said there was a shortage of trainee doctors specialising in acute medicine and this had led to pressure on hospital units.
They warned that as the number of people admitted to acute hospital departments rises, it was vital health boards implement a range of measures to fill recruitment gaps and organise patient flows better.
They also said there was other medical areas could provide alternatives to acute admissions, through improved outpatient access to special clinics and community services.
Professor Derek Bell, president of the Royal College of Physicians of Edinburgh, said: "Our longer term shared goals must be to grow the workforce and to restore a more appropriate balance between service delivery and the standards of training. Trainee satisfaction levels relating to being on call for acute medicine must improve."
Dr Frank Dunn, president of the Royal College of Physicians and Surgeons of Glasgow, added: "The training component of unscheduled care has been subsumed by service delivery because of the dependency of trusts and health boards on junior doctors in this critical area.
"Systems must be put in place where there is an appropriate balance between training and service delivery which is driven by the level of expertise of each trainee. The experience of trainees in unscheduled care is likely to be greatly enhanced by achieving the appropriate degree of support and supervision."