Two breakthrough medicines will be available free for Australians with extremely rare and life-threatening inherited diseases.

The drugs will help save the lives of newborn babies and offer an easy oral alternative to treatments delivered by in-hospital infusions.

Kanuma (sebelipase alfa) and Cerdelga (eliglustat), which both treat enzyme deficiency diseases, were added to the Life Saving Drugs Program (LSDP) this month.

Kanuma is the first effective treatment discovered for infantile onset lysosomal acid lipase deficiency, or LAL-D. Without the treatment babies born with the condition do not survive more than 12 months.

Cerdelga is listed for treatment of Gaucher disease (Type 1), as an oral alternative to treatments delivered by infusions. The disease is caused by deficiency of an enzyme required to break down fats, which build up in the spleen, liver and bone marrow.

Cerdelga will be available for patients aged 18 years and over who've had 12 months prior treatment with one of the 3 other enzyme replacement therapies for Gaucher disease (Type 1) listed on the LSDP, all of which require infusion.

Gaucher disease (Type 1) is a lifelong condition with symptoms that include an enlarged abdomen, bone pain, fractures, fatigue and bruising.

The LSDP is separate to the Pharmaceutical Benefits Scheme, providing free access to highly specialised medicines to treat patients with ultra-rare and life-threatening diseases.

The latest listings will expand the LSPD to a total of 18 medicines for 11 diseases.

Minister for Health and Aged Care Mark Butler said the changes could save patients hundreds of thousands of dollars a year.

"Australia is one of the first countries in the world to subsidise Kanuma. Parents will no longer have to watch their baby born with LAL-D grow sicker, or literally spend a fortune to buy this drug," he said.

"The listing of Cerdelga will also provide great relief for adults with Gaucher disease type 1, who will be able to take a capsule and get on with their lives instead of going to hospital for an infusion."

Professor Stephan Opat, Director of Clinical Haematology at Monash Health, said the goal of treatment is to help people affected by the symptoms of Gaucher disease enjoy as normal a life as possible.

"The availability of an oral therapy suitable for the majority of patients represents a significant shift from intravenous therapy in the management of Gaucher disease Type 1," he said.