Health services are failing to identify the specific healthcare needs of lesbian and bisexual women, according to a survey by gay rights charity Stonewall.
In particular, the survey of 6,000 lesbian and bisexual women has revealed disturbing levels of self-harm, substance abuse and exclusion from routine testing for cervical cancer.
Stonewall also claims that healthcare providers are failing to address specific mental health needs that many women still experience as a result of discrimination.
Ruth Hunt, Stonewall Head of Policy and Research, said: "This vital new intelligence provides a wake-up call to healthcare practitioners across the country. It also demonstrates that hundreds of thousands of lesbian and bisexual women feel highly uncomfortable when engaging with the NHS.
"Women who are deterred from visiting their GP, or coming out to them, are less likely to be treated early and appropriately, with inevitably higher costs for the NHS when accurate diagnosis finally takes place."
Key results from the survey include: one in five lesbian and bisexual women have deliberately harmed themselves in the last year, compared to 0.4% of the general population; young lesbian and bisexual women are 10 times more likely to have self-harmed compared with others; and lesbian and bisexual women under 20 are eight times more likely to have attempted to take their life than teenagers generally.
In addition, the survey indicates that lesbian and bisexual women are five times more likely to have taken drugs than women generally, and that 40% drink three times a week compared with a quarter of women in general.
New legislative protections introduced in 2007 made it unlawful to discriminate against lesbian and bisexual women in the delivery of public services, yet half still report having had negative experiences in the health sector in the last year.
One in five who have not had a cervical smear test were told, wrongly, by healthcare practitioners that they are not at risk. Fifteen per cent of lesbian and bisexual women over 25 – almost double the number of women in general – have never had a cervical smear test.
Ben Summerskill, Stonewall Chief Executive, said: "Lesbian and gay taxpayers fund 60,000 posts within the NHS. What lesbian and bisexual women have revealed should disturb any healthcare practitioner, and encourage the NHS to take their statutory obligations towards these women more seriously.
"This report also provides compelling evidence that the current duty on health services to provide equality of treatment on grounds of gender, ethnicity and disability should be extended to sexual orientation."
The report includes 10 key recommendations for the NHS to improve the efficiency and effectiveness of service delivery for lesbian and bisexual patients.
A spokesman for the Department of Health said that it took seriously any differences in health between different groups, and pledged to work with Stonewall.