Doctors in Victoria will be able to prescribe the HIV prevention drug PrEP under new changes announced by the State Government.

The drug is taken by people who are HIV negative to prevent them from becoming infected, but has not been approved by the Therapeutic Goods Administration (TGA).

The new guidelines will now allow doctors to prescribe the drug to high-risk people until it is approved by the TGA.

The New South Wales Government announced a clinical trial for the pill would be held in the state.

Health Minister Jill Hennessy said the guidelines would give doctors more certainty when prescribing the drug.

"Many people are buying PrEP online, some doctors are prescribing it with risk," Ms Hennessy said.

"We want to actually make sure that doctors have legal clarity and the ability to prescribe offline PrEP, that means the generic product."

The drug has been approved for use in the United States and France.

Ms Hennessy said it was only a matter of time before the drug was approved in Australia.

"We're certainly all on the pathway to PrEP becoming a normalised part of HIV prevention and what the Government today is doing is we are fast-tracking a group of specially trained doctors' ability to prescribe it while those processes take place," she said.

The Doherty Institute's Professor Sharon Lewin was encouraged by the Government's announcement and said she would like to see the drug made available on the PBS.

"I 100 per cent believe that the PBS must support this and that's the best way to support a drug reimbursement, but we need to do something in the intervening 12 to 18 months that we're going to face not having it," she said.

The Victorian AIDS Council's Simon Ruth echoed those sentiments and said the drug had proven effective in preventing people from contracting the disease.

"PrEP is more effective then condoms. If you're on PrEP daily you will not contract HIV, if you're a HIV negative gay man we can not say the same about condoms, which are only 70 per cent effective," he said.