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6 Health Benefits of Saint John’s Wort

Written by Helen Quach, BS (Biochemistry) | Last updated:

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Saint John's Wort

Saint John’s wort is a medicinal plant that can help treat depression, improve brain function, kill bacteria, and more. Read below to learn more about its health benefits.

What is Saint John’s Wort?

Saint John’s wort (Hypericum perforatum) is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. The flowering tops of St. John’s wort are used to prepare teas, tablets, and capsules containing concentrated extracts. Liquid extracts and topical preparations are also used [1].

St. John’s wort contains hypericin and hyperforin, which both have health benefits [2].

However, St. John’s wort interacts with many medications, making the medications less effective [1].


  • The probable mechanism of the St. John’s wort action is the suspension of monoaminoxidase (MAO) as well as the suspended reuptake of serotonin [3].
  • Inhibits COX2, IL-6, iNOS [4].
  • Inhibits STAT-1 [4].
  • Inhibits PGE2 [4].

Health Benefits of Saint John’s Wort

1) Can Treat Depression

Depression may originate from a disruption of normal brain chemistry, specifically from a deficiency of neurotransmitters like acetylcholine, norepinephrine, dopamine, and serotonin. Antidepressant drugs typically raise the levels of those neurotransmitters [4].

Hypericin is the main antidepressant constituent of St. John’s wort because it stimulates capillary blood flow. Hypericin also helps regulate dopamine levels and increases the number of receptors in rat brains [4].

The administration of St. John’s wort is clearly helpful in treating mild to moderate depression. All the recent clinical trials suggest that St. John’s wort is more tolerable than synthetic antidepressants as it causes fewer side effects [4].

2) Kills Bacteria and Viruses

Extracts of St. John’s wort have been used for thousands of years to treat cuts, abrasions, and other wounds. It is also useful in reducing inflammation, which is related to its antibacterial properties [4].

The main antibacterial component is hyperforin. Hyperforin inhibits the growth of certain types of microorganisms [4].

Extracts of St. John’s wort are effective against various classes of viruses. Flavonoid and catechin-containing fractions of Saint John’s wort are active against influenza virus [4].

Hypericin inactivates enveloped viruses at different points in the viral life cycle and also inhibits the ability of viruses to fuse with cell membranes [4].

3) May Have Anticancer Properties

In cells, hyperforin inhibits tumor cell growth [4].

Hypericin is also an anticancer agent, reportedly inhibiting the growth of cancer cells derived from a variety of tissues [4].

4) Has Antioxidant and Neuroprotective Properties

Extracts of St. John’s wort decreased oxidative stress and consequently prevent brain damage, inflammation, and gastrointestinal problems. Thus, it may effectively treat oxidative stress-related brain disorders such as Parkinson’s and Alzheimer’s diseases [4].

The flavonols quercetin and kaempferol in St. John’s wort provide neuroprotective action by decreasing oxidation.  Thus, the plant serves as a brain-protecting agent against Parkinson’s disease in mice [4, 5].

5) Can Reduce Withdrawal Symptoms

St. John’s wort may act by activating the opioid receptors without causing withdrawal symptoms. It decreased the effects of opiate withdrawal in rats. The effectiveness of H.perforatum is equivalent to clonidine, an FDA-approved medication for treating withdrawal symptoms [4].

6) May Treat Premenstrual Syndrome

Premenstrual syndrome (PMS) is a common condition. Serotonin might play a role in the production of PMS symptoms. Saint John’s wort influences the serotonergic system [6].

Daily treatment with Hypericum perforatum was more effective than placebo treatment for the most common physical and behavioral symptoms associated with PMS [7].


Many drugs interact badly with Saint John’s wort including SSRIs, statins, warfarin, and contraceptives. They can be a dangerous combination when taken together [8].


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About the Author

Helen Quach

BS (Biochemistry)

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