Making sure your children's asthma is properly treated can significantly increase the likelihood they will not have the condition as an adult, new research has found.

The landmark study, to be presented at a major lung and respiratory conference in Adelaide, reveals how well asthma symptoms are controlled in children aged under five can predict whether they will have the condition as they get older.

Lead researcher Francine Ducharme, from the University of Montreal, studied almost 120,000 children under five with asthma.

"In the first two years after diagnosis, those kids whose asthma was well controlled had 78 per cent increased chance of outgrowing asthma compared to those whose asthma wasn't managed properly," she said.

"It opens a window of opportunity to treat children properly and influence how the disease progresses."

Many toddlers not getting correct medical treatment

Experts said these latest findings were concerning in light of another study that showed many Australian children with asthma were not getting medical treatment in line with national guidelines.

Nusrat Homaira, from the University of New South Wales's paediatric department, found many children were using combination inhalers first without using inhaled corticosteroid.

"From 2014-2016, each year 5,000 children under five were given fixed dose combination inhalers, which they are not supposed to get at all," she said.

"Children under five given combination inhalers have an increased risk of hospitalisation and developing resistance to the drug."

Up to 40 per cent of children with asthma will not outgrow the condition and will have the illness into adulthood.

Professor Ducharme said the main message from her research was that parents should not be complacent when it comes to treating asthma in kids.

"To our knowledge ours is the first study to combine all the factors for affecting disease remission and focus on what is potentially modifiable, namely asthma control," she said.

"The best way we know to achieve good control of asthma at present is to take long-term effective medications."