A survey of trainee dermatologists found more than 80 per cent were against potential reforms which could see them covering night and weekend shifts for hospitals.
The results were revealed at the British Association of Dermatologists' Annual Conference in Glasgow.
Across the UK the NHS is faced with an increase in frail elderly patients and a recruitment crisis in acute and emergency medicine.
The Future Hospital Commission, established by the Royal College of Physicians to consider these problems, proposed that all doctors pursuing careers in medical fields should be given general internal medicine training.
Dr Danny Kemmett, a dermatologist in Glasgow and a member of the Dermatology Council for Scotland, said trainees were concerned this would reduce the time they had to learn their specialty and "expose them to a situation where they fear they may harm the patient because they do not have the necessary skills".
Dr Kemmett added: "There are a number of specialties that share the same concerns, particularly neurology, gastroenterology and rheumatology."
Professor Chris Bunker, President of the British Association of Dermatologists, said: "This study highlights a major flaw in the agenda to make participation in general medicine mandatory for those training in all medical specialties."