Campaigners have welcomed the relaxation of rules which prevented some gay and bisexual men donating blood.
Men who have sex with men (MSM) in a long-term relationship will be able to give blood from next summer, NHS Blood and Transplant (NHSBT) said.
Under previous rules, all MSM had to abstain from sex for three months to donate.
The Terrence Higgins Trust charity welcomed the news, saying the move will make for a “fairer blood donation system” while also ensuring its safety.
Changes will be made to the donor health check questionnaire, introducing new behaviour-based deferrals to assess potential donors against high-risk sexual behaviour such as having multiple partners or taking part in “chemsex”.
The biggest change to the rules means anyone who has the same sexual partner for more than three months will be eligible to donate if there is no known exposure to a sexually transmitted infection (STI) or if there has been use of anti-HIV drugs PreP or PEP, said NHSBT.
It added: “Donors will no longer be asked to declare if they have had sex with another man, making the criteria for blood donation gender neutral and more inclusive.
“A set of other deferrals will also be introduced for the other higher risk sexual behaviours identified, such as if a person recently had chemsex, and updated for anyone who has had syphilis.”
Su Brailsford, associate medical director at NHSBT, said: “Patients rely on the generosity and altruism of donors for their life-saving blood.
“We are proud to have the safest blood supply in the world and I’m pleased to have concluded that these new changes to donor selection will keep blood just as safe.
“We will keep collaborating with and listening to LGBT representatives, patients and current donors to make sure by summer 2021, when we bring about these changes, that our process for getting accurate information from donors about their sexual behaviours is inclusive and done well.”
The change was brought about by recommendations from the Fair (For the Assessment of Individualised Risk) steering group and has been fully accepted by the Department of Health and Social Care.
Fair concluded the new deferral system will maintain the safe supply of blood in the UK, where there is a less than one in a million chance of not detecting a hepatitis B, C and HIV infection in a donation, according to NHSBT.
Dr Michael Brady, medical director at the Terrence Higgins Trust, said: “Welcome changes include the differentiation between oral and anal sex, and for those whose partner is HIV positive and virally supressed due to six months or more of adherence to treatment.
“There is certainly more work to do and we will continue to work to ensure that our blood donation service is inclusive and evidence based.
“We now need to look at the restrictions in place for other groups, including former injecting drug users, to see if we can safely make the blood donation eligibility even more inclusive.”
A full report is due to be published on Monday morning, NHSBT added.
The Committee on the Safety of Blood, Tissues and Organs recommended in 2011 that the lifetime ban on gay and bisexual men donating blood be lifted and it was reduced to a one-year abstinence from sex requirement.
In 2017, it was cut to a three-month requirement.