When Sunshine Coast marketer Kyanne Hooper's 16-month-old son Myles became sick, a doctor gave her a script for liquid antibiotic Azithromycin for children. But it was another matter finding a pharmacy that had it.

"We tried a number of different chemists," she said.

"We had one chemist look at all the stock on the Sunshine Coast and just say, 'There's none here.'"

Eventually, she was able to find a chemist who gave her the adult medication, quartered into a child's dose, which she then ground and gave to young Myles. 

"It doesn't taste pleasant no matter how you try to disguise it and you can't negotiate with a 16-month-old," she said.

Ms Hooper said it was worrying to know that the shortage was already severe when it was only the early weeks of winter.

"I've got kids at school and in daycare, and there just seems to be so much respiratory illness in the community at the moment."

Ms Hooper is among a number of parents going from pharmacy to pharmacy to find the medication that is used to treat chest infections, whooping cough, and other respiratory issues in children.

The liquid version of Pfizer's Azithromycin has been listed as being in a critical shortage across the country by the Therapeutic Goods Administration (TGA).

It is unlikely to return to shelves until late November. 

There is also a shortage of its alternative Clarithromycin due to manufacturing issues, which will last until the end of August.

Pharmacists seeing desperate parents 'daily'

Sunshine Coast pharmacist James Lester said he regularly spoke to families needing the unavailable medication for their kids.

"Unfortunately, it's happening daily," Mr Lester said.

"And they're seeking antibiotics, and they've been to five, seven or 10 pharmacies and unfortunately we just don't have it."

Mr Lester said there were alternatives, but the medication was often used for those with chronic lung conditions.

"It's for some of the young children who are often the sickest in the community," he said.

Mr Lester said health professionals felt terrible when they had to turn away a patient or family in need.

"We will do the absolute best we can to create a solution, whether that's with their GP or specialist or with the patient themselves," he said.

"But, unfortunately, there are cases where we just can't do that.

"We have to either turn the patient away or, if it is a serious enough case, we have to advise them to seek hospital treatment."

Regional, rural families have it even harder

Mr Lester said he felt for those living outside major centres, who might not have access to multiple pharmacies.

"Unfortunately, the shortages can be worse," he said.

"They are smaller pharmacies holding less stock and, unfortunately, they're just not able to keep up with the pace and be able to access the medication."

That is the world that Erin Collin lives in, at her Blackbutt home about 2.5 hours' drive north-west of Brisbane.

She was the first to contract mycoplasma, followed by her three-year-old daughter Brydee about five weeks ago, as the shortage became more serious.

Ms Collin said it was a hard-fought battle even then to find what they needed.

"I've only got one chemist and one GP in my town at Blackbutt," she said.

"You feel very helpless as a mother because it's one thing having a sick child, but then it's another when you can't source a medication that's prescribed them."

But after finding then giving the three-day prescribed dose, young Brydee again became sick, which meant another GP appointment and another hunt for medicine.

"I was fortunate there was a chemist in Kingaroy that still had one left in stock after the initial ring around.

"I went and grabbed that as fast as I could."

Even third alternative hard to find

Queensland GP Cathryn Hester said that even when families were prescribed an alternative, they often found those too were unavailable.

Dr Hester said it was a difficult situation, but asked families to be patient with their doctors and health professionals.

"We understand that it's very stressful, especially for parents who are trying to care for unwell children," she said.

She said GPs and pharmacists worked closely to find a treatment solution, potentially issuing a new script for a medication that was more readily available.

New figures from the federal health department found cases of RSV, COVID-19, and influenza had steadily risen since April, indicating the start of Australia's flu season.

In Queensland, there have been 3,783 cases of whooping cough, or pertussis, diagnosed as of June 9.

The average over the previous four years for this time of year was just 242.

Hundreds of medications face shortage

Across all medications, there are 424 facing a "current shortage" across Australia, while this specific antibiotic is in a critical shortage along with 40 others.

The TGA warns a further 11 medications are likely to become critical in the coming weeks.

A spokeswoman for the TGA said it was aware of the shortages, and has approved an overseas-registered alternative temporarily, but it will not be subsidised by the Pharmaceutical Benefits Scheme.

"[The TGA] is working with pharmaceutical companies to help manage these shortages and facilitate supply," she said.

Supply shortages 'unavoidable'

Health Minister Mark Butler said medicine shortages were unavoidable, partly as a result of the COVID pandemic.

He said shortages could be caused by a lack of raw materials, natural disasters, or increased demand.

He said the government was building Australia's capacity to manufacture critical medical supplies and working to ensure stock levels by keeping minimum levels of key medications in stock.