Compulsory uniforms at Perth's Fiona Stanley Hospital have created problems for almost everyone that wears them, according to the Health Services Union (HSU).

HSU Secretary Dan Hill says union members are reporting comfort and safety issues with the uniform.

The cut of the pants is understood to be particularly tight, so much so that it has forced some staff to seek medical certificates exempting them from wearing it.

Mr Hill said in an interview with the ABC that “the hospital is looking at the changes to the uniform”.

“But,” he said, “that's taking time and in the meantime there are a lot disgruntled allied health and health science employees out there”.

One concern is that non-nursing staff are given just three uniforms, as opposed to the four to six sets given to their colleagues.

The HSU also has concerns with Fiona Stanley Hospital’s requirement for clinical psychologists and clinical neuro-psychologists to wear uniforms.

The union says it does not know of any other hospital with such requirements.

Mr Hill said it presented problems.

“They believe and have the support of their professional association, the Australian Psychological Society, that [the] wearing of a uniform can have and does have negative impacts on their capacity to interact with their patients, the therapeutic engagement is affected,” he said.

There is a risk to confidentiality too, as some patients do not want to be seen consulting with a clearly-marked psychologist.

Exemptions have been granted to workers in mental health wards, but the union says the broader the issue has now escalated to a dispute.

Fiona Stanley Hospital social workers face similar problems with the mandatory uniform policy.

“There are members of the public who have difficulty identifying with authority and uniforms represent an authority figure to them and certainly in all hospitals' social workers, those working in front line mental health services, don't wear uniforms for that very reason,” he said.

The Health Department says a working group has been formed to look at the issues, and replacement made-to-measure uniforms can been offered in some circumstances.

The Department’s statement said the hospital had already sought advice from the Australian Psychology Association, and pledged to continue to work with the unions and staff on the issue.