St. John’s wort is a common supplement marketed for easing the symptoms of depression, but it can have side effects. Here’s what we know.

St John's wort, a yellow flower used in herbal medicineShare on Pinterest
Albert Fertl/Getty Images

Natural remedies are appealing for many who want to heal, including people living with depression or experiencing depressive symptoms. Natural approaches are common and are a part of the rich cultural history of many people.

If you’ve been looking for natural remedies for depression, chances are you’ve come across a supplement called St. John’s wort, which has been around for thousands of years. But does St. John’s wort help with depression, and what are the side effects?

St. John’s wort (Hypericum perforatum) is a flowering plant used to make herbal medication. Some research evidence says it can improve your mood, possibly by affecting the levels of serotonin in your body — a similar mechanism for some antidepressants.

Natalie Fraize, a licensed professional counselor and mental health counselor, says that “while in the United States St. John’s Wort is sold as a supplement, in Europe, it is still prescribed to treat depression.”

In general, St. John’s Wort may be used to treat many ailments, from insomnia to muscle aches. It’s available as a pill, topical treatment, and as a liquid (tincture).

“[St. John’s wort] has been used for thousands of years as a traditional medicine around the world,” says Fraize. “Both the Greeks and Romans reported its use early on for the treatment of depression.”

According to the National Center for Complementary and Integrative Health (NCCIH), there is a fair amount of research on the short-term effects of St. John’s wort on depression. Still, there is far less research about its long-term effects.

The research on whether St. John’s Wort effectively treats depression is mixed.

Some experts say St. John’s wort seems to reduce the severity of depression symptoms. But more research is needed before we truly know how effective the supplement is.

The NCCIH cites a 2008 review of 29 international studies that suggested that “St. John’s wort may be better than a placebo and as effective as different standard prescription antidepressants for major depression of mild to moderate severity.”

However, a 2011 NCCIH and NIMH-funded clinical trial with 73 participants found that St. John’s wort and an antidepressant called citalopram (a selective serotonin reuptake inhibitor or SSRI) decreased symptoms of minor depression the same amount as a placebo.

Also, a 2016 systematic review of St. John’s wort for major depressive disorder found that the supplement was more effective than a placebo for mild and moderate depression. But it should be noted that this research did not include results for severe depression.

Based on this research, the effectiveness of St. John’s wort may vary between people and research studies. A good next step would be consulting with your doctor or psychiatrist to see what option is best for you, especially if you’re looking for a natural remedy.

The Food and Drug Administration (FDA) has not approved St. John’s wort for depression. As Fraize also notes, supplements are less regulated than drugs in the United States, making an accurate recommendation on dosage hard to come by.

However, according to Dr. Sam Zand, ​​psychiatrist, founder, and chief medical officer of Better U, the most commonly studied dose of St. John’s wort is about 900 mg, and people often take this dosage as 450 mg twice daily or 300 mg 3 times a day.

Note that it’s very important to consult a doctor before using St. John’s wort, as this dose can be dangerous or lethal for some people.

It’s important to consult with your doctor or pharmacist before introducing any new supplement, and St. John’s wort is no exception. It can have various side effects and interact with your existing medications, including antidepressants.

St. John’s wort can interact with some antidepressants to cause severe or fatal consequences. There is a risk of a potentially life threatening increase in your serotonin levels.

“If you have been taking an antidepressant and recently stopped, consider speaking with your doctor before taking St. John’s wort as your serotonin level may still be elevated,” suggests Fraize.

St. John’s wort can also reduce the effectiveness of some medications, including:

  • contraceptive pills
  • heart medication called digoxin
  • an immunosuppressant called cyclosporine
  • a pain reliever called oxycodone
  • some drugs for HIV, such as indinavir
  • some cancer drugs, such as irinotecan
  • a blood thinner called warfarin

Also, St. John’s wort may become toxic even if you aren’t taking other medications. The enzymes that break down this medication may not function properly in some people. Different types of food can also alter these enzymes, which makes it hard to predict who can safely take this medication.

According to Zand, it’s best to start low and increase the dosage slowly to monitor for initial side effects and allow the body to get used to the herbal medication slowly.

The NCCIH lists the following side effects of St. John’s wort as minimal and uncommon:

  • confusion
  • dizziness
  • dry mouth
  • headache
  • fatigue
  • sexual dysfunction
  • sensitivity to sunlight
  • upset stomach

The NCCIH also notes reports of St. John’s wort worsening psychosis symptoms in those with bipolar disorder or schizophrenia.

Fraize recommends watching for foods and drinks containing a chemical called tyramine when taking St. John’s wort. “There can be a potentially dangerous interaction when St. John’s wort is combined with tyramine […] This combination can lead to high blood pressure, fast heart rate, and becoming delirious.”

Examples of foods high in tyramine include strong or aged cheeses, cured meats, pickled or fermented foods, and dried or overripe fruits.

St. John’s wort and infertility

Some evidence suggests that St. John’s wort could reduce fertility by affecting sperm movement, according to a 1999 laboratory study, and eggs, according to a 1999 animal study.

A 2006 review states that it’s not advisable to use St. John’s wort during pregnancy until high quality human studies have shown it to be safe.

There is some evidence that St. John’s wort could help with depression symptoms. But experts say it’s important that people do not try to treat depression at home or use St. John’s wort to replace traditional depression treatments.

From vitamins to foods and psychedelic therapy, there are various alternative (and natural) approaches to treat depression.

One of the best places to start to support yourself and your mental health is to speak with a licensed mental health professional about all of the choices you have available to you. If you need help finding a professional, you can explore Psych Central’s How to Find Mental Health Support resource.

And remember, naturally or not, you are not alone, and you deserve to feel better and happier.