Cancer medications and a treatment for a rare genetic disease have been added to Australia's Pharmaceutical Benefits Scheme.

The newly-listed drugs are used for patients with skin cancer, lung cancer and X-linked hypophosphatemia or XLH, a disorder which impacts bones and growth.

Australia has become the first country in the world to subsidise treatment for that condition, saving patients up to $360,000 a year.

Endocrinologist and head of medicine at Monash Health Professor Peter Ebeling said the subsidy was "a major milestone that will be warmly welcomed by Australians living with XLH and their families", some who had waited 40 years for a new treatment option.

"To date, treatment has not addressed the underlying cause of XLH," he said.

"Now, we can stop the loss of phosphate that causes the multiple health problems seen in XLH rather than trying to close the gate once the horse has bolted."

For the first time Australians with a common form of skin cancer will also be able to access immunotherapy Cemiplimab at an affordable price.

Health Minister Mark Butler said greater access to the drug via the PBS would improve the lives of people living with the condition.

From November 1 more lung cancer patients will also be able to access treatments atezolizumab and tepotinib.

PBS medications will cost a maximum of $30 per script from 2023.

It's expected around 1800 people a year will benefit from the changes announced on Saturday.

It comes as more Indigenous Australians become eligible for COVID-19 antivirals.

Aboriginal and Torres Straight Islander people with just one risk factor can now access molnupiravir, nirmatrelvir and ritonavir.