St. John’s Wort: 10 Potential Health Benefits, Dosage, And Side Effects

Medically reviewed by Gaelle Clement, Natural Health Practitioner, Naturopath
Written by Sindhu Koganti

St. John’s Wort is scientifically known as Hypericum perforatum. It is a flowering plant native to Europe. It has been used in folk medicine for centuries to treat many ailments. The extracts of St. John’s Wort contain active ingredients like hypericin and hyperforin. The plant is said to possess anti-inflammatory, antimicrobial, antioxidant, and anticancer properties. This herbal medicine may help treat depression, control menopausal symptoms, heal wounds, improve attention deficit hyperactivity disorder (ADHD), and treat anxiety disorder.

In this article, we will discuss the health benefits, dosage, and potential side effects of St. John’s Wort. Keep reading.

What Are The Benefits Of St. John’s Wort?

1. May Help Treat Depression

St. John’s Wort may help treat depression. Generally, medications such as antidepressants are used to treat this psychological issue. Antidepressants usually come with other side effects. St. John’s Wort is said to possess some active ingredients like hyperforin, adhyperforin, and hypericin that may increase the levels of chemical messengers in the brain (1).

A study stated that participants who took St. John’s Wort were far less likely to experience adverse events than those using antidepressants (2). In addition, using St. John’s Wort reduces the symptoms of depression to a similar extent as antidepressants (3).

Another study conducted by the University of Queensland supported the use of St. John’s Wort in treating mild depression (4). A review of 29 international studies suggests that St. John’s Wort may be better than a placebo and as effective as different standard prescription antidepressants that are used to treat depression (5).

2. May Control Menopausal Symptoms

St. John’s Wort extract may be used to relieve the psychological and vegetative symptoms of menopause. It could improve the quality of life and hot flashes in perimenopausal women. Further larger clinical trials are needed to further understand this mechanism (6).

In another study, 111 women supplemented with 900 mg of St. John’s Wort daily for 12 weeks showed improvements in their menopausal symptoms (7). Another study states that the plant can be used as an effective treatment for the vasomotor symptoms of perimenopausal or postmenopausal women (8).

Also, the extracts of St. John’s Wort and their combination with herbs have shown fewer side effects in postmenopausal women (9). Daily treatment with St. John’s Wort was more effective for the treatment of premenstrual syndrome (PMS) (10).

3. May Help In wound healing

St. John’s Wort is traditionally used to treat wounds and burns (11), (12). The extracts of this herb have also been used as a folk remedy to promote skin wound healing (13). St. John’s Wort also resulted in a faster inflammatory response and helped in healing diabetic surgical wounds (14).

This herbal medicine and its metabolite (hyperforin) were found to help in the treatment of inflammatory skin disorders (15). St. John’s Wort was found to treat wounds as a result of collagen synthesis and fibroblast migration (16).

4. May Treat Attention Deficit Hyperactivity Disorder (ADHD)

St. John’s Wort may help treat attention deficit hyperactivity disorder (ADHD). A study conducted by the Regional Hospital Bozen, Bolzano, found that St. John’s Wort showed a slight improvement in the mean scores of the patients’ hyperactivity and immaturity factors (17).

However, a study that used St. John’s Wort extract to treat children and adolescents with ADHD did not improve their symptoms (18). Hence, more long term research is required to further understand this benefit of St. John’s Wort.

5. May Treat Anxiety disorder

St. John’s Wort possesses some beneficial therapeutic properties that may help treat anxiety disorder. The plant has antidepressant properties that are used in the treatment of the major depressive disorder (MDD) with comorbid anxiety (19). A study conducted by the Western Illinois University on mice found that St. John’s Wort helped in the treatment of posttraumatic stress disorder (which includes anxiety disorder) (20).

However, more research is warranted in this regard.

6. May Treat Atopic dermatitis

Hyperforin, a major constituent of St. John’s Wort, has an anti-inflammatory effect. The topical application of St. John’s Wort cream may help in treating atopic dermatitis (21).

Constituents of the plant, like hyperforin and hypericin, possess antioxidant, anti-inflammatory, anticancer, and antimicrobial properties that could help treat atopic dermatitis (22). Also, hypericin is a photosensitizer that can be used for selective treatment of non-melanoma skin cancer (22).

More research is needed in this regard.

7. May Treat Somatoform Disorders

Somatoform disorders are mental disorders that manifest themselves as physical injuries. Initial studies have shown that St. John’s Wort may possess some efficacy in patients with somatoform disorders (23). In another study, administration of 600 mg of St. John’s Wort extract daily was effective in the treatment of somatoform disorders (24).

8. May Reduce Cancer Risk

Hyperforin and its derivatives (like aristoforin) are natural products of St. John’s Wort that have several pharmacological properties. Hyperforin is said to be a potent anticancer agent (25). The melatonin‐rich germplasm line of St. John’s Wort is said to possess antioxidant properties. They help inhibit cancer cell growth (26).

Hyperforin also promotes the programmed cell death of various cancer cells and inhibits their capacity to migrate (27), (28). Hyperforin and its derivatives hold a prominent position as anticancer medications with their low toxic nature and anti-tumor properties (29). A study stated that hyperforin could induce cancer cell death in the case of leukemia (30), (31).

9. May Treat Sinus Congestion

Some studies suggest that St. John’s Wort may work against sinusitis and seasonal affective disorder (SAD) (32). St. John’s Wort has antibiotic and antiviral properties that may help relieve phlegm congestion, sinus infection, flu, and bronchitis symptoms. However, further research is needed to understand this benefit of St. John’s Wort in humans.

10. May Lower Blood Pressure

St. John’s Wort has strong anti-inflammatory and antioxidant properties, which may help lower blood pressure. Some anecdotal evidence suggests that this medicinal herb minimizes inflammation in the cardiovascular system and decreases stress on the heart. However, more research is warranted in this regard.

Insufficient evidence to rate effectiveness for

St. John’s Wort has a long history of use in folk medicine for treating a diverse range of disorders that include inflammation, wounds, bacterial and viral infections, peptic ulcers, and respiratory impairments (33). St. John’s Wort is said to possess analgesic and antinociceptive properties that help in the management of pain (34). Multiple sclerosis (MS) is a central nervous system disorder that is characterized by axonal injury and inflammation. St. John’s Wort is said to possess anti-inflammatory properties that help treat multiple sclerosis (MS) (35).

The strong anti-inflammatory properties of St. John’s Wort make it an ideal solution for severe joint pains, gout, and muscle spasms. The ethyl acetate extract of St. John’s Wort could show antihyperglycemic activity in diabetic rats (36). Animal studies state that St. John’s Wort has hepatoprotective effects that could help treat hepatic ischemia in rats (37). St. John’s Wort may help fight against diabetes. The administration of its extracts (125 and 250 mg/kg) induced a significant decrease in high blood glucose levels in diabetic rats (38).

Following are some of the purported benefits of St. John’s Wort that have insufficient evidence:

  • Brain tumor (glioma)
    John’s Wort may help treat glioma through intravenous injection (39). However, insufficient data is available to prove this claim.
  • Herpes

Recent studies have shown that St. John’s Wort contains certain antiviral properties. This herb is believed to be helpful in the treatment of herpes, AIDS, hepatitis B, and several other serious viral conditions (40), (41).

  • Smoking cessation

St. John’s Wort could attenuate nicotine withdrawal signs in mice. The plant was also used as a natural antidepressant in mice. More studies in humans are needed (42). St. John’s Wort proves to be effective in larger controlled studies. It could represent a less expensive, more readily accessible, and well-tolerated agent to promote tobacco cessation (43). However, further studies are necessary to understand the possibility of St. John’s wort in the treatment of smoking cessation in humans.

  • Helps create a hormonal balance

St. John’s Wort is a widely popular treatment for hormonal imbalances. Its chemical composition is especially shown to lower the hormonal imbalances in a menopausal woman. It may reduce mood swings, the severity of the cramps, irritation, depression, and anxiety levels (44). However, further evidence is needed to confirm its effectiveness.

Other potential benefits of St. John’s Wort that lack any research include the following:

  • Migraine headache
  • Obsessive-compulsive disorder (OCD)
  • Skin redness and irritation (plaque psoriasis)
  • Tooth pulling
  • Nerve pain
  • Burning mouth syndrome
  • Post-operative pain

Though more research is warranted, the plant does have some benefits. In the following section, we will look at the ideal dosage of the plant.


For Children and young adults (>18 years)

  • For ADHD – 300 mg St. John’s Wort, three times daily for eight weeks (18)
  • For depression – 150-1800 mg St. John’s Wort, three times daily for eight weeks (41)

For Adults

  • For anxiety – 900 mg St. John’s Wort, twice daily for twelve weeks (45)
  • For cancer – 05-0.50 mg per kg of hypericin, for two months (46)
  • For mild to moderate depression – 20-1800 mg St. John’s Wort, three times for 4 to 52 weeks
  • For severe depression – 900-1800 mg, once daily for 8 to 12 weeks (47)
  • For obsessive-compulsive disorder (OCD) – 450-1800 mg, once daily for 12 weeks (48)
  • For premenstrual syndrome (PMS) – 300-900 mg daily for two menstrual cycles (49)
  • For smoking cessation – 300 mg, once or twice daily for three months (50)

 *These values are taken only from randomized clinical trials. They are for reference only. None of them have been proven to treat any particular ailment. Consult your doctor for more information.

Though St. John’s Wort is generally safe for consumption, it also may have some side effects. We will explore them in the following section.

What Are The Potential Side Effects Of St. John’s Wort?

The uncontrolled and unprescribed dosage of St. John’s Wort may cause several side effects. These include allergic reactions, sedation, gastrointestinal symptoms, headache, skin reactions, dry mouth, tiredness/restlessness, and dizziness. The majority of these reactions were generally considered to be mild, moderate, or transient (51), (52), (53).

Some research has indicated that taking certain herbal supplements, including St. John’s Wort, may increase your risk of complications if you are put under anesthesia. You should not take St. John’s Wort at least two weeks before a scheduled surgery (54).

Photosensitivity reactions affecting the skin are other serious adverse reactions associated with St. John’s Wort. Recent data suggest that photosensitivity reactions are dose-related, with increased sensitivity associated with higher doses. Extracts of St. John’s Wort are used in the treatment of depression. They contain various substances with naphthodianthrones hypericin and pseudohypericin as characteristic ingredients. These compounds may lead to phototoxicity in animals and humans (55), (56).

Also, St. John’s Wort may cause liver injury, tingling, and erectile or sexual dysfunction. However, limited research is available in this regard.

Possible Drug Interactions

St. John’s Wort may react with certain drugs. Generally, most herbs interact with prescribed drugs and have the potential to influence metabolic reactions (56), (57).

In a study, drug interactions with St. John’s Wort had affected the organ systems and the central nervous system. St. John’s Wort and fluoxetine have a similar profile, and this demonstrates that herbal preparations can result in adverse drug reactions that are similar to those of prescription medications (58). In another study, St. John’s Wort interacted with cyclosporin A metabolism. The drug is involved in the careful monitoring of blood levels in a patient after liver transplantation (59).

St. John’s Wort may interact with medicines such as warfarin, phenprocoumon, cyclosporine, oral contraceptives, theophylline, digoxin, indinavir, and lamivudine (60).

Also, it may interact with other drugs. These include:

  • Antibiotics, antidepressant SSRIs, and Triptans

St. John’s Wort may interact with selective serotonin reuptake inhibitors (SSRIs). This interaction may lead to agitation, nausea, confusion, and diarrhea (56).

  • Oral contraceptives

St. John’s Wort may interact with oral contraceptives. This results in breakthrough bleeding among women who are taking birth control pills along with St. John’s Wort  (56).

  • Immunosuppressants and blood thinners such as warfarin

Warfarin may interact with St. John’s Wort, which can lead to severe adverse reactions that are sometimes life-threatening (61).

  • Sedatives and medications used to treat generalized anxiety disorder; drugs used to treat cancer, heart conditions, and HIV/AIDS

From one study, patients with HIV experienced an increase in HIV RNA viral load following the use of St. John’s Wort (56).

  • Over-the-counter medications (for sleep, cough, and cold)

St. John’s Wort also interacts with anticonvulsants such as carbamazepine, phenobarbitone and phenytoin, theophylline, cyclosporin, phenprocoumon, and digoxin. However, more long-term research is needed to further understand these drug interactions.


St. John’s Wort is an effective dietary supplement and medicinal herb for treating various nervous system related disorders. It is said to possess anti-inflammatory, antimicrobial, antioxidant, and anticancer properties and helps to treat many ailments. It may help treat depression, control menopausal symptoms, help in wound healing, and treat anxiety disorders. However, excess and unprescribed usage of this herbal drug may lead to some adverse reactions. Hence, limit its usage and consult your health care provider in case of any medical emergencies.

Frequently Asked Questions

How long does St. John’s Wort take to start working?

St. John’s Wort may take 3 to 6 weeks to show any effects. Do not stop taking it all at once, as you may otherwise experience side effects.

Should I take St. John’s Wort in the morning or night?

St. John’s Wort works best if taken twice a day. In the third and fourth weeks of your treatment, take 300 mg in the morning and 600 mg in the evening. In the fifth week, consider increasing the dose to 600 mg twice a day. Like all antidepressants, it can take four to six weeks before you feel any benefits. Consult your doctor for more information on the use and dosage.

Does St. John’s Wort make you gain weight?

No. St. John’s Wort has the potential to prevent obesity and abnormalities with lipid metabolism. It does not lead to weight gain.

Is St. John’s Wort bad for your heart?

St. John’s Wort is well known to help treat depression in heart patients, with less negative side effects on the heart than traditional antidepressants.

Can St. John’s Wort damage the liver?

St. John’s Wort has not been linked to liver injury. Because of its many herb-drug interactions and effects, the herb may affect liver function or cause some liver injury. Avoid taking it along with liver medications. Consult your doctor.

Can you drink alcohol with St. John’s Wort?

You should avoid or limit the use of alcohol while being treated with St. John’s Wort. Alcohol can increase the side effects of St. John’s Wort associated with the nervous system, including dizziness, drowsiness, and difficulty concentrating.


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Sindhu Koganti is a Biotechnology graduate and has been in the writing field for over 4 years now. She specializes in writing on Health and Wellness. She has hands-on experience in writing articles and press releases on Life Sciences and Healthcare, Food and Beverages, and Chemicals and Materials. When she’s not writing, she loves watching movies and listening to music. She also enjoys traveling.