Depression affects more than 300 million people around the world, including 1 in 10 adults in the US alone (, ).
While many drugs effectively treat depression, some people prefer to use natural or alternative remedies.
St. John's wort is a medicinal plant that has been used for centuries to treat depression, among a host of other conditions.
St. John's wort, botanically known as Hypericum perforatum, is a wild plant native to Europe and Asia. It has yellow, star-shaped flowers.
It's traditionally harvested around St. John's Day in late June — hence the name.
The plant's flowers and buds can either be dried and made into capsules and tea or pressed for use in oils and liquid extracts.
It's most commonly used to treat depression and associated conditions, such as anxiety, sleep problems and seasonal affective disorder.
While it's usually taken orally in the form of capsules, tea or liquid extract, it can also be applied directly to the skin as an oil.
In the US, it's classed as a dietary supplement by the Food and Drug Administration (FDA) and not approved as a prescription medicine for depression.
However, it's one of the most commonly purchased herbal products in the US.
Summary: St. John's wort is a wild plant. Its flowers and buds are commonly used as an alternative treatment for depression and other conditions.
While St. John's wort's effects on your body are not fully understood, it's thought to work similarly to antidepressants.
Research suggests that a number of its active ingredients, including hypericin, hyperforin and adhyperforin, may be responsible for these benefits.
These ingredients appear to increase the levels of chemical messengers in the brain, such as serotonin, dopamine and noradrenaline. These then act to lift and regulate your mood ().
Interestingly, St. John's wort doesn't have some of the common side effects of prescription antidepressants, such as loss of sex drive.
Summary: St. John's wort is thought to regulate mood by increasing the levels of several chemical messengers in the brain.
There is strong evidence to support the use of St. John's wort in the treatment of depression.
In 2016, an in-depth review of 35 studies examined these effects.
It found that St. John's wort ():
- Reduced symptoms of mild and moderate depression more than a placebo
- Reduced symptoms to a similar extent as prescription antidepressants
- Appeared to have fewer side effects than prescription antidepressants
- Doesn't seem to reduce sex drive, a common side effect of antidepressants
However, there was a lack of research on its effects on severe depression.
Another recent analysis looked at 27 studies comparing the effects of St. John's wort and antidepressant medication. It showed that St. John's wort had effects similar to those of antidepressants on mild to moderate depression.
It also found fewer people stopped taking St. John's wort during the studies, compared to antidepressants. This could be due to its fewer side effects ().
Furthermore, in one controlled study, 251 people who took 900–1,800 mg of St. John's wort for six weeks experienced a 56.6% decrease in their depression score, compared to a 44.8% decrease in those on antidepressants ().
Lastly, another controlled study in 241 people taking either St. John's wort or an antidepressant found that 68.6% of people experienced a reduction in symptoms with St. John's wort, compared to 70.4% of those on an antidepressant ().
Summary: Studies show that St. John's wort appears to be as effective as antidepressants in treating mild to moderate depression. It also appears to have fewer side effects.
St. John's wort has also been researched for other conditions, including:
- Premenstrual syndrome (PMS): A study found that St. John's wort supplements reduced symptoms of PMS. However, a more recent review of studies didn't find it any more effective than a placebo (, ).
- Wound healing: When applied to the skin, it has been found to effectively treat pressure sores, wounds, bruises, burns and hemorrhoids (, ).
- Symptoms of menopause: One small study found a significant reduction in menopause-related symptoms after taking liquid St. John's wort extract, compared to a placebo ().
- Seasonal affective disorder (SAD): SAD is a form of depression that occurs during the winter months. There is fairly weak evidence supporting the use of St. John's wort supplements in the treatment of SAD ().
- Cancer: Test-tube studies have shown that the hypericin in St. John's wort can inhibit tumor cell growth. However, it's not recommended as a cancer treatment due to its potential interaction with other cancer medications (, ).
Furthermore, some claim that it can be used to treat obsessive-compulsive disorder (OCD) and help people quit smoking.
However, there is currently no evidence to support these claims.
Summary: There is some evidence that St. John's wort can be helpful as an alternative treatment for PMS, wound healing and symptoms of menopause.
While St. John's wort appears to be a relatively safe supplement, there are a few things to consider before taking it.
Most people who take St. John's wort do not experience any side effects.
However, some people do report side effects, including trouble sleeping, upset stomach, irritability, fatigue and skin rashes.
Nevertheless, research shows that it has considerably fewer side effects than antidepressant drugs (, , , ).
Moreover, it is associated with fewer distressing symptoms, such as increased sweating, sexual dysfunction and fatigue ().
On rare occasions, St. John's wort can cause a sensitivity to sunlight, both for the skin and eyes. This appears to be related to high doses (, ).
It's important to note that most of its reported side effects are also common symptoms of depression. That's why it helps to be aware of how you're feeling before beginning to take St. John's wort.
Pregnancy and Breastfeeding
A small number of observational studies have looked at the risk of taking St. John's wort during pregnancy.
They found preterm birth rates were not affected. However, one of the studies found a small increase in the risk of malformations (, ).
However, midwives often recommend St. John's wort for postpartum depression.
Only a small number of studies have looked into its effects on breastfeeding. They show that it can be transferred into breast milk at very low levels, but that it doesn't appear to cause side effects in breastfed babies (, ).
Due to a lack of evidence, it's not possible to definitively say whether St. John's wort is safe to use during pregnancy or breastfeeding.
The evidence on St. John's wort causing withdrawal symptoms is mostly anecdotal.
Some people report symptoms like sickness, dizziness and anxiety after they stop taking it abruptly.
To be safe, it's generally recommended to slowly reduce your dosage before discontinuing your use of St. John's wort.
Summary: Some side effects have been reported with the use of St. John's wort. However, research consistently shows that it has fewer side effects than standard antidepressant medications.
St. John's wort interacts with a large number of commonly prescribed medications.
In most cases, it decreases their effects, but it can also increase them, potentially resulting in more frequent and severe side effects.
It's known to interact with the following medications, among others:
- Antidepressants: It can increase side effects when taken with some antidepressants. This can lead to serotonin syndrome, a rare condition in which levels of serotonin become too high and, in extreme cases, can be fatal (, ).
- Birth control pills: Unexpected bleeding can occur mid-cycle with the combined use of birth control pills and St. John's wort. It may also decrease the effectiveness of birth control (, ).
- Warfarin: Warfarin is a blood-thinning medication commonly used to prevent heart attacks, strokes or blood clots. St. John's wort has been found to decrease its effectiveness, increasing the risk of blood clots ().
- Cancer medication: St. John's wort has been shown to reduce the effectiveness of some cancer drugs (, ).
- Xanax: It has been shown to reduce the effectiveness of Xanax, an anxiety medication ().
Summary: St. John's wort has been found to interact with many common medications. It is important that you speak to your doctor before taking it if you are currently on any other medications.
St. John's wort comes in many forms, including tablets, capsules, teas, extracts and oils for the skin.
The standard strength is 0.3% hypericin ().
But given that the FDA does not recognize it as a drug, it is not regulated as such and products can vary greatly in strength.
This makes accurate dosing difficult to determine, but most studies on St. John's wort and depression have used a dose of 300 mg three times a day (900 mg daily) ().
Capsules or tablets seem to allow for more accurate dosing. Buying it from a reputable source can further ensure accurate dosing.
Summary: Accurate dosing can be difficult to determine. The standard strength is 0.3% hypericin, while the standard dose for depression is 300 mg taken three times a day.
Studies show that St. John's wort can be as effective as antidepressants in treating mild to moderate depression — and has fewer side effects.
Additionally, some evidence supports its use for the treatment of PMS, wound healing and symptoms of menopause.
The main concern is its interaction with a large number of common medications, so it's important to speak to a doctor before taking it.