Australians are at risk of wasting hundreds of dollars on intravenous infusion "cocktails" marketed with dodgy and misleading promises, the medical regulator warns.

The Australian Health Practitioner Regulation Agency has this week put several businesses on notice, warning their marketing tactics for intravenous infusion treatments may be against national law.

The law prohibits advertising that makes misleading or unfounded claims.

While intravenous infusion treatments are increasingly on offer in Australia, the medical justification and scientific evidence behind them has not kept pace with advertising, the agency's chief executive Martin Fletcher said.

"Clinics charging hundreds of dollars for cocktails promising everything from boosting immunity, clearer thinking, beauty, and even anti-ageing, need to be honest with their clients about the lack of scientific evidence supporting their infusion services," he said.

"Patients also need to be aware of infection and other risks which come with all medical treatments, and which is why clinical interventions should only be provided when they are necessary."

Intravenous infusions are invasive procedures that carry inherent health and safety risks for patients, according to the agency.

Businesses advertising the infusions commonly claim they can improve health, wellness, or appearance, and quote patients as feeling or looking better after they receive them.

However, the agency says there is little to no evidence to support such generalised claims, therefore making them against the law.

Advertisers also make claims about the supposed improvements being attainable, even when there's no diagnosed clinical need for a given compound in an infusion, the agency said.

Legislation outlaws advertising that encourages people to use regulated health services indiscriminately or unnecessarily.

"Anecdotal evidence is not acceptable evidence for the purposes of substantiating claims about the potential benefits of health services, and this type of advertising can encourage indiscriminate or unnecessary use of regulated health services," the agency said in a statement.

Health practitioners can expect to come under scrutiny if they are found administering intravenous therapy outside of professional codes of conduct, the agency warned.