The MDDUS has dealt with calls from GP members unsure of the boundaries when dealing with patients wanting to mix NHS and private care, with many doctors asking if they can see their own NHS patients privately.
MDDUS medical adviser Dr Naeem Nazem said: 'One common query we encounter is doctors asking if they can prescribe privately for their NHS patients. One example is a doctor wanting to prescribe a flu vaccine privately for a patient who is not eligible to receive it on the NHS criteria.
'In short, the answer is no, with the only exception being when the appropriate treatment is not available on the NHS.
'It can be a potentially serious ethical issue if the correct steps aren't taken. Any act of perceived dishonesty can lead to GMC sanctions and the risk of erasure.
'Doctors should keep a clear separation between NHS and private treatment and must act openly and honestly to ensure there can be no perceived conflict of interest. This includes providing the patient with all the necessary information to help them make their choice of treatment.
'If the doctor believes a private assessment or treatment is required, then they are obliged to refer the patient and cannot make any financial gain from the patient - either directly or indirectly.
'If a patient wishes to seek treatment privately, then they would be referred, with all relevant information about the patient including medical history being provided.'
Patients are entitled to opt in and out of NHS treatment at any stage - as long as they are entitled to the NHS treatment and they are treated in the same way as those receiving all of their care within the NHS.
Dr Nazem said: 'Doctors should ensure a patient has all the relevant information when choosing private or NHS treatment, with any private treatment being delivered separately from NHS care.
'Some MDDUS members have received complaints from patients who believed they were being treated on the NHS, only to find themselves being billed for private treatment.
'Doctors who have a financial or commercial interest in, for example, a pharmacy, pharmaceutical or medical devices company, must ensure they do not allow that interest to affect decision making regarding patient care.'
Conflicts of interest are not always avoidable. The MDDUS dealt with one case where a patient was referred to a specialist orthopaedic surgeon who happened to be the doctor's husband.
Dr Nazem added: 'The specialist was perceived as being the most suitable person to assess the patient so, in order to avoid any problems, the doctor would need to ensure the patient was aware of this information and other options available to them. Any potential conflict of interest should be recorded in the patient's records.'