Immunocompromised Australians will have free access to the shingles vaccine in an expansion of the immunisation program.

The free vaccine program will now be made available to anyone over 18 who is immunocompromised due to health conditions or a side effect of treatment.

The program was previously available only to immunocompromised people at high-risk, along with people over 65 and Indigenous Australians over 50.

It's estimated more than 200,000 people will now have access to the free vaccine following the expansion.

Shingles is a reactivation of the same virus that causes chickenpox and can cause a painful rash and lead to nerve pain months after the infection.

Health Minister Mark Butler said the federal government would spend more than $57 million in expanding the vaccine program.

"It expands what is already the most comprehensive shingles vaccine program on the planet," he told ABC's Insiders program on Sunday.

"(Immunocompromised people) are about twice as likely as the general population to contract shingles, which can be a very, very serious illness."

More than 1.3 million people have already received the free vaccine since the immunisation program started in November 2023.

"Without listing it on the National Immunisation Program, Australians who are immunocompromised due to an underlying health condition would have to pay up to $560 for their vaccine," Mr Butler said.

"Without vaccination, almost one in three Australians will get shingles in their lifetime."

Crohn's Colitis Australia chief executive Leanne Raven welcomed the decision to expand the program.

"Australians living with autoimmune diseases such as Crohn's or ulcerative colitis, need as much support as possible to avoid developing conditions that can further impact their day-to-day life," she said.

"Conditions like shingles, which is more common in older people as well as people with a weakened immune system, can be debilitating."