Health professionals in England are to be told to ask patients aged 16 or over about their sexual orientation, under new NHS guidelines. NHS England said no-one would be forced to answer the question but recording the data would ensure that "no patient is discriminated against".
The guidance applies to doctors and nurses, as well as local councils responsible for adult social care. A spokeswoman said: "It will have no impact on the care [people] receive."
She added: "All health bodies and local authorities with responsibility for adult social care are required under the Equality Act to ensure that no patient is discriminated against."
NHS England recommends health professionals - such as GPs and nurses - ask about a person's sexual orientation at "every face to face contact with the patient, where no record of this data already exists".
But the Family Doctor Association said it was "potentially intrusive and offensive" for GPs to monitor people's sexuality. Chairman Dr Peter Swinyard told the BBC that for older patients in particular, sexuality "doesn't affect health outcomes or care".
NHS England said the data was already being collected in many areas but that the new guidance makes it standard, and that it expects sexual orientation monitoring to be in place across England by April 2019. Under the guidance, health professionals are to ask patients: "Which of the following options best describes how you think of yourself?".
NHS England said lesbian, gay and bisexual (LGB) people were "disproportionately affected" by health inequalities such as poor mental health and a higher risk of self-harm and suicide. It said public bodies had a legal obligation to pay regard to the needs of LGB people under the Equality Act 2010.
"Collecting and analysing data on sexual orientation allows public sector bodies to better understand, respond to and improve LGB patients' service access," the guidance states.
Paul Martin, chief executive of Manchester's LGBT Foundation, which worked with NHS England and others to develop sexual orientation monitoring, said he was "so proud" of the new standard. He said earlier this week: "If we're not counted, we don't count."