Asthma Australia says its investigation has also found that almost two-thirds of South Australians with asthma don't have an action plan, while a third of the 5754 emergency department presentations in 2016/17 were considered avoidable.

"In 2016, 45 people in South Australia died because of their asthma. Around 70 per cent of those deaths may have been prevented," Asthma Australia chief executive Michele Goldman said.

"We need to be doing all we can to make sure that people with asthma are best supported to avoid these preventable deaths."

Friday's report found that for every 100,000 children in SA, 361 were admitted to hospital for asthma, compared with the national average of 309.

One of those was four-year-old Marley Heinze-Faulkner who had his first serious attack in May this year.

"He was having his puffer but his breathing kept getting worse throughout the day," his mother Ellen said.

"We took him to hospital and he was pretty freaked out, but he was given medication and oxygen, and they kept him in for 24 hours until he stabilised."

Ms Heinze-Faulkner said before the admission the family didn't really know much about asthma. They were referred to Asthma Australia's COACH program, which provides specialised advice through scheduled calls.

Ms Heinze-Faulkner said help provided since then had helped them greatly while the appointment of an asthma educator had been a "godsend".

Ms Goldman said asthma was a chronic disease that could be life-threatening.

"But with good support, people with asthma can manage their condition every day, and live a full and productive life," she said.

Australian Associated Press