The yellow-flowering plant is commonly used as a herbal alternative to treat depression, however, new research suggests it could produce the same adverse side effects as pharmaceutical antidepressants.

A research team from the University of Adelaide in Australia compared the effects of St. John's Wort against those of fluoxetine -- better known by the trade names of Prozac and Sarafem -- a commonly prescribed antidepressant.

St. John's Wort should be considered a drug like any other, says Claire Hoban, a PhD candidate at U of A, for it can bring about side effects such as dangerous increases in body temperature and blood pressure.

"There is a common belief that because something is natural and can be purchased from a health food shop without a prescription, it's safe," says Hoban. "However, people need to start thinking of St John's Wort, and other herbal medicines, as a drug and seek advice from a qualified healthcare practitioner to be sure they use it safely."

Adverse reactions from St. John's Wort are fewer than those stemming from fluoxetine, for 84 adverse reactions of the former were reported between 2000 and 2013 whereas adverse reactions to fluoxetine numbered 447 during that period.

Yet the reactions to both treatments were of a similar nature, involving anxiety, panic attacks, dizziness, vomiting, amnesia and aggression, according to Hoban.

"It's concerning to see such severe adverse reactions in our population, when people believe they are doing something proactive for their health with little risk."

St. John's Wort is available over the counter in most countries, and the real danger comes when individuals take it concurrently with other medications -- especially pharmaceutical antidepressants, the contraceptive pill and certain blood thinners.

"Most people taking St John's Wort will not have any adverse reactions; however, those who do take it should tell their doctor and pharmacist," says Dr. Ian Musgrave of U of A.

The study was published in the journal Clinical and Experimental Pharmacology and Physiology.

Last year, a US research team arrived at the same conclusion and their paper was published in The Journal of Alternative and Complementary Medicine.

"Patients may have a false sense of safety with so-called 'natural' treatments like St. John's wort," said lead author Sarah Taylor, M.D., of Wake Forest Baptist Medical Center. "And it is crucial for physicians to know the dangers of 'natural' treatments and to communicate the risks to patients effectively."