A "game-changing" drug which dramatically reduces the chances of being infected with HIV is to be made available on the NHS in Scotland.
The Scottish Medicines Consortium (SMC) has agreed to approve the treatment, which is known as Prep.
Scientists have found that a daily dose of the drug can protect people at risk of contracting the virus.
It means Scotland will become the first place in the UK to routinely offer Prep to eligible patients.
Campaigners welcomed the SMC's decision, describing it as a "bold step" which could lead to a reduction in the spread of the virus.
They estimate that up to 1,900 people north of the border could benefit from the drug, which has the brand name Truvada and costs about £450 a month.
Safe sex practices
The anti-retroviral drug is already licensed for use by people diagnosed with HIV in Scotland.
However, the SMC's decision relates to its use on a preventative basis by people who do not have the virus.
The group said Prep was one aspect of a wider HIV prevention strategy and it should be used in combination with safe sex practices such as using condoms.
SMC chairman Dr Alan MacDonald said: "[Prep] when used together with safer sex practices may help to reduce the spread of HIV, which is an ongoing priority for the Scottish government."
It was one of series of drugs approved by the body, including Kadcyla, which is used to treat aggressive and advanced types of breast cancer.
What does Prep do?
Pre-exposure prophylaxis (or Prep for short) is a small, blue pill.
The pill works by protecting cells in the body and disabling the virus to stop it multiplying - should it enter the body.
Taking it once a day has been found to reduce the risk of HIV infection by 86%.
It is currently used in the US, Canada, Australia and France to help protect gay men at the highest risk of contracting HIV.
The decision on Prep was welcomed by a group of charities, including HIV Scotland and the Terrence Higgins Trust Scotland, which had campaigned as The Prep4Scotland Coalition.
In a statement, they said: "We applaud the SMC for taking this bold step to tackling HIV in Scotland.
"Prep provides opportunities to reinvigorate how people at higher risk of HIV exposure engage with testing and prevention opportunities, and it is a vital opportunity to make a real reduction in the number of new HIV transmissions.
"All NHS Boards in Scotland need to now follow the SMC's advice and ensure they're making Prep available to those who need it, so that no-one at risk is left behind."
Robert McKay, the national director for the Terrence Higgins Trust Scotland, said the move could save the health service thousands of pounds.
"Today, Scotland has made history in the fight against the HIV epidemic," he said.
"Prep can now be used as a vital tool - alongside condom use, regular testing and early treatment - to help bring an end to HIV transmission in Scotland.
"Not only will this make a life-changing difference to individuals by protecting them from a lifelong and stigmatised condition, but for every person who would have become HIV positive without Prep, NHS Scotland will save £360,000 in lifetime treatment costs."
Earlier, HIV Scotland's chief executive George Valiotis said that there was a growing demand for the treatment in Scotland.
He estimated that "a couple of dozen" Scots are already using variants of the drug after buying generic versions online.
'Why I buy Prep'
Watty Gaffney is one of about "a couple of dozen" people in Scotland already thought to be buying generic versions of Prep online.
"I started taking it at the turn of the year. I'd been thinking about it for some time. I'd been reading up on Prep and what that means for people.
"It is essentially a preventative treatment for HIV. It seemed the natural way to move forward.
"You come into contact with people throughout your life. You don't know their history. You want to protect yourself and it seemed like the appropriate thing to do."
HIV Scotland believes the use of Prep has played a part in reducing the number of HIV infections in Scotland.
The latest figures from Health Protection Scotland show 285 new cases of HIV were reported in 2016, down from an annual average of 359 over the last five years.
The manufacturer of Truvada, Gilead, applied to the SMC after they were urged to do so by the Scottish government last year.
It followed a series of legal battles in England over whether the NHS or local authorities should pay for the medication.
The Court of Appeal eventually ruled that NHS England had the power to fund the drug,
The decision did not mean that NHS England had to fund Prep but in December it announced plans for a large scale clinical trial of the drug, expected to involve 10,000 participants over three years.