A review setting out the circumstances in which people can pay privately for drugs while still receiving NHS care is being announced by the government.
A report by Professor Mike Richards is expected to address the principle of allowing top-ups in relation to a whole range of diseases and conditions.
It will also cover concerns such as what happens if a patient runs out of money, and what agreements can be made with drug companies.
The government has previously stated that patients cannot be both an NHS patient and a private patient in the same episode of care. But it is common knowledge that with the connivance of some NHS hospitals, 1,000 patients a year already top up their care with private drugs.
The hospitals allow patients to see a consultant and treat that as one episode of care, while another consultant writes a private prescription for drugs that are supplied to the patient's home by a private firm.
The NHS Confederation director of policy, Nigel Edwards said: "This change in policy is welcome and helps deal with a situation which had become insupportable."