A report from Queensland's health watchdog is calling for medical workers in hospitals to take the concerns of patients' relatives more seriously.
The Health Quality and Complaints Commission analysed 172 complaints over three years and found more than 40 per cent of them were serious.
It found that hospitals failed to recognise family warnings about the rapid deterioration in the condition of their relatives.
Assistant commissioner Dr John Rivers says ignoring warnings can cause harm to patients.
"These are a series of complaints about deterioration, most of them relatively severe events where there was potential for significant patient harm," he said.
"What we've learned from this is that deterioration can be a very rapid process, so it's important to respond to any signals that alert you to that.
"And particularly when patients and their families and their carers feel that there's been significant deterioration, that often should prompt a rapid clinical response."
Dr Rivers says hospitals can improve their responses to concerns raised by families.
"That's particularly true with ill patients and with children and for people where there is substantial risk of sudden changes in the clinical condition, unwell patients," he said.
Dr Rivers says the complaints the commission looked at only represent a "tiny percentage of events in the healthcare system".
However, the commission recommends doctors rapidly reassess a patient's condition if there are concerns from a family member.
"Everybody involved in the care needs to be alert to the process of clinical deterioration," Dr Rivers said.
"If anybody, the patient, the actual family or the carer and anyone in the clinical team - the nursing staff and the medical staff - are concerned about deterioration, then there needs to be a rapid reassessment of the clinical situation."
He says a lot of the problems are often systemic.
"The easy response is to blame individuals, but in fact many of these clinicians probably had high workloads and many sick patients," he said.
"[Doctors] obviously can't be with them all at the same time so much of the issue may be systemic rather than individual."