ADELAIDE, Australia, July 2 (UPI) -- The herbal medicine St. John's Wort can cause the same adverse reactions as prescribed antidepressants, and taking both together can have serious side effects, according to researchers.
St. John's Wort is available over the counter, without a prescription, and is often used to treat depression, anxiety and tiredness.
"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," said Claire Hoban, a pharmacology Ph.D. student at the University of Adelaide, in a press release. "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."
Researchers compared adverse reaction reports for St. John's Wort and fluoxetine, also known as Prozac, finding that the two drugs have the same potential adverse reactions, which include anxiety, panic attacks, dizziness, vomiting, amnesia and aggression.
Between 2000 and 2013, Hoban said researchers found 84 reports of adverse reactions to St. John's Wort and 447 to fluoxetine. She cautioned, however, that in addition to knowing fewer people use St. John's Wort, those people are less likely to report an adverse drug reaction because they don't consider the herbal medicine to be a drug.
Based on the research, Dr. Ian Musgrave, of the University of Adelaide's Discipline of Pharmacology, said he'd like to see bottles of St. John's Wort to have improved warning labels that include explanations of potential adverse reactions.
"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," Musgrave said. "It's important that doctors and pharmacists know about all the drugs their patients take, not just prescription drugs, because herbal medicines like St John's Wort can have serious reactions with some pharmacy medicines, like antidepressants, the contraceptive pill and some blood thinners."
The study is published in Clinical and Experimental Pharmacology and Physiology.