What You Need to Know About St. John’s Wort

Used in traditional medicine as far back as ancient Greece, St. John’s wort is a perennial plant (a plant living more than two years) with yellow flowers. The name St. John’s wort is believed to be derived from John the Baptist, as the plant blooms in late June, around the time of the St. John the Baptist feast.

Historically, St. John’s wort has been used to help heal wounds and treat a variety of health conditions, including kidney and lung ailments, insomnia, and depression. Currently, St. John’s wort is most commonly used to address mood disorders, particularly depression, and symptoms such as nervousness, fatigue, and difficulty sleeping. (10)

How does St. John’s wort work?

The medicinal parts of the St. John’s wort plant include its flowers and, to a lesser extent, its leaves. The main active components are napthodianthrones (e.g., hypericin and pseudohypericin), phloroglucinols (e.g., hyperforin), and flavonoids (e.g., quercetin, kaempferol, and luteolin).

It was formerly believed that hypericin was the component of St. John’s wort primarily responsible for its antidepressant action, however, it is now understood that hyperforin, adhyperforin, and several other related compounds are the primary active constituents. These chemicals act on messengers in the nervous system that regulate mood. (8)

St. John’s wort benefits

St John’s wort is believed to increase the activity of brain chemicals such as serotonin, dopamine, gamma aminobutyric acid (GABA), and norepinephrine that play an important part in regulating our mood. (4)

St. John’s wort for depression

Oral intake of St. John’s wort extract appears to improve mood and decrease nervousness and fatigue related to depression. In a study of 251 individuals with acute major depression, those who took 900 mg to 1800 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 individuals taking pharmaceutical antidepressants. St. John’s wort was also found to be better tolerated. (13)

Furthermore, a 2016 review of studies evaluated the effectiveness of St. John’s wort in the treatment of Major Depressive Disorder (MDD). The review included 35 previously published studies, including a total of 6993 participants. Researchers determined that St. John’s wort supplementation reduced symptoms of mild to moderate depression more than a placebo and similar to prescription antidepressants. However, the review also noted that there was a lack of research examining the effects of St John’s wort for severe depression, as well as poor reporting of adverse events. (3)

St. John’s wort for sleep

St. John’s wort supplementation is often used to improve sleep. While there is little research examining the effects of St. John’s wort on sleep, some evidence suggests that this herb may be beneficial by prolonging the duration of deep sleep, a stage of sleep important for physical and mental recovery.

Furthermore, other research suggests that St. John’s wort primarily affects sleep patterns, rather than overall sleep quality. In one study, 12 participants were given either 300 mg of St. John’s wort three times per day or a placebo over a 4-week period. Individuals who supplemented with St. John’s wort increased the time spent in deep sleep compared to the placebo. No differences in sleep onset or sleep continuity were observed. (12)

St. John’s wort for anxiety

While much of the research examining the use of St. John’s wort has been conducted in individuals with depression, according to the Anxiety and Depression Association of America, an estimated 50 percent of people with depression also suffer from some form of anxiety disorder. (2)

It has therefore been theorized that St. John’s wort may benefit individuals with anxiety due to its effect on the activity of serotonin, dopamine, GABA, and norepinephrine. However, long-term human studies examining the effectiveness of St. John’s wort in managing anxiety are needed. (5)

St. John’s wort for menopause symptoms

As a result of declining estradiol levels around menopause, many women experience symptoms such as hot flashes. St. John’s wort has been found to have molecular components similar to those of human hormones, and therefore, it has been suggested as a possible intervention to reduce menopausal symptoms. (1)

In a systematic review, researchers evaluated the possible benefits of black cohosh, St. John’s work, chasteberry, vitamins and minerals, or their combination, on menopausal symptoms. The results suggest the combination of black cohosh and St. John’s wort to be more effective at improving menopausal symptoms when compared to placebo. Black cohosh alone and a combination of St. John’s wort and chasteberry were not found to be superior to the placebo. (9)

St. John’s wort side effects

St. John’s wort is generally considered safe when it is taken orally in appropriate doses. However, possible side effects include:

• Difficulty sleeping
• Dizziness
• Dry mouth
• Headache
• Irritability
• Nervousness
• Restlessness
• Skin rash or tingling
• Tiredness
• Upset stomach or diarrhea (6)

St. John’s wort has also been associated with potentially serious interactions with certain medications. Possible medication interactions include:

• Antidepressants
• Birth control pills
• Cyclosporine, which prevents the body from rejecting transplanted organs
• Digoxin, a medication used to treat heart failure
• Some HIV drugs, including Indinavir
• Some cancer medications, including Irinotecan
• Warfarin, a blood thinner (10)

St. John’s wort increases the brain chemical called serotonin. As a result, taking it with other antidepressants or drugs that affect serotonin may further increase serotonin levels, causing serious side effects, such as heart problems, shivering, and anxiety. (11)

There currently isn’t enough reliable information available to determine if St. John’s wort is safe when it is applied topically. (7)

The bottom line

St. John’s wort has been studied most extensively as a treatment for depression. Most studies demonstrated that St. John’s wort may help address mild-to-moderate depression, with fewer side effects than most other prescription antidepressants.

As always, be sure to speak to your integrative healthcare provider to identify potential interactions and to determine if a St. John’s wort supplement is right for you.