St. John’s wort, (Hypericum perforatum), is a flowering plant native to Europe, Asia, and parts of Africa. It has been used for centuries as a herbal remedy for various health conditions. The plant’s bright yellow flowers contain active compounds such as hypericin, hyperforin and flavonoids, which are believed to contribute to its medicinal properties.

St. John’s Wort Active Ingredients

In St. John’s Wort, the medicinal properties are primarily attributed to the aerial parts of the plant, including the flowers and leaves. The primary active constituents in St. John’s Wort include; hypericin, hyperforin, pseudohypericin and other flavonoids, which are thought to be the major sources of antidepressant activity.

St. John’s Wort is thought to work by increasing levels of serotonin, dopamine, and other neurotransmitters in the brain, similar to the mechanism of action of some antidepressant medications.

Medical Components in St. John’s Wort

Different parts of the St. John’s Wort plant contain varying levels of active ingredients. The aerial parts of the St. John’s wort plant, particularly the flowers and leaves, are primarily used for medicinal purposes. These parts contain the highest concentrations of the active compounds, including hypericin, hyperforin, and flavonoids, which are believed to contribute to the plant’s therapeutic effects.

Here’s a breakdown of the medicinal components in different parts of the plant:

Flowers: The yellow, star-shaped flowers of St. John’s Wort are commonly used for medicinal purposes. These flowers contain various compounds, including hypericin and hyperforin, which are believed to contribute to the herb’s therapeutic effects.

Leaves: While the flowers are the primary focus, the leaves of St. John’s Wort also contain some of the active compounds. However, the concentration of these compounds is generally lower in the leaves compared to the flowers.

Medicinal Uses of St. John’s Wort

St. John’s Wort has been traditionally used to alleviate symptoms of mild to moderate depression and anxiety. The compounds in St. John’s Wort are thought to have antidepressant and anti-inflammatory properties.

Below we will explore these health benefits in more detail:

St. John’s Wort for Depression

St. John’s Wort has become popular again as an antidepressant. Also known as Perforate, it is the number one treatment for depression in Germany and has been extensively studied by Commission E, the scientific advisory panel to the German government.

Neurotransmitters in St. John’s Wort

In several studies of laboratory animals and humans, one or more of the chemicals in St. John’s wort appeared to delay or decrease re-absorption of the neurotransmitters dopamine, norepinephrine and serotonin by nerve cells.

Neurotransmitters are chemicals that carry messages from nerve cells to other cells. Ordinarily, once the message has been delivered, neurotransmitters are re-absorbed and inactivated by the cells that released them. Chemicals in St. John’s wort may keep more of these antidepressant neurotransmitters available for the body to utilise.

Multiple studies have shown that St. John’s wort may be effective in relieving mild to moderate depression, although maximum antidepressant effects may take several weeks to develop.

Anti-Viral Effects of St. John’s Wort

Possible antiviral effects of St. John’s wort are being investigated for the treatment of HIV/AIDS, hepatitis C and other viral illnesses.

Some preliminary research suggests that St. John’s wort may exhibit antiviral activity against certain viruses.

For example:

Herpes Simplex Virus (HSV): In laboratory studies, extracts of St. John’s wort have shown inhibitory effects against herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2), which are responsible for oral and genital herpes infections, respectively. These effects may be attributed to the presence of bioactive compounds such as hypericin and hyperforin.

Influenza Virus: Some studies have suggested that St. John’s wort extracts may have inhibitory effects against influenza viruses, including influenza A and influenza B strains. However, further research is needed to fully understand the mechanisms of action and potential clinical applications.

It is thought that hypericin, pseudohypericin and other chemicals in St. John’s wort may stick to the surfaces of viruses and keep them from binding to host cells.

Another theory is that St. John’s wort may contain chemicals that interfere with the production or release of viral cells. This antiviral activity is enhanced greatly by exposure to light.

It’s important to note that while these findings are promising, more research is needed to determine the effectiveness of St. John’s wort as a treatment for viral infections in humans. Additionally, the safety and efficacy of St. John’s wort can vary depending on factors such as dosage, formulation, and individual health status. However, the doses needed for active antiviral effect from St. John’s wort may be so high that it may limit its usefulness as an antiviral.

Other Uses of St. John’s Wort

It is believed that chemicals in St. John’s wort may act like other chemicals that are associated with relieving emotional conditions.

St. John’s wort has been studied for the treatment of emotional disorders such as ;anxiety, obsessive-compulsive disorder (OCD), menopausal mood swings and premenstrual syndrome. In laboratory studies, it has shown some effectiveness for lessening the symptoms of nicotine withdrawal and for reducing the craving for alcohol in addicted animals.

St. John’s Wort has been used to treat hypothyroidism.

A salve made with the extract of St. John’s Wort can be used topically to treat bruises, burns, insect bites and scabies.

How to Take St. John’s Wort

The flowers of St. John’s wort are typically harvested when they are in full bloom during the summer months. After harvesting, they can be dried and used to prepare herbal teas, tinctures, extracts or capsules.

While the flowers are the most commonly used part of the St. John’s wort plant for medicinal preparations, some herbalists also use the leaves in certain formulations. However, the flowers are generally preferred due to their higher concentration of active compounds.

The appropriate dosage and formulation may vary depending on the specific health condition being treated.

Always take care when taking herbs and Read Our Disclaimer.

St. John’s Wort Notes / Side Effects

Latin Name

Hypericum perforatum

Common Names

Amber Touch-and-Heal, Hardhay, Hypericum, Klamath Weed, Millepertuis, Rosin Rose, SJW, Tipton Weed, Perforate St John’s-wort, Common Saint John’s wort, St John’s wort.

Properties of St. John’s Wort

Strengthens the nervous system and speeds healing. Analgesic (pain relieving), Antidepressant, Antiviral, Anti-inflammatory, Antispasmodic, Diuretic (increases the flow of urine), Emmenagogic (Promotes menstrual flow), Nutritive tonic.

St. John’s Wort is Indicated for:

Hypothyroidism, neuralgia, sciatica and back pain, spinal issues, pain from deep wounds, mild depression (not severe depression), shingles, cold sores and herpes, joint pain, aging, trauma, eczema, stomach ache, colic, lung congestion, insomnia, anemia, headaches, jaundice, catarrh, carcinoma (type of cancer), bed wetting, melancholy, uterine cramps, menstrual problems, antidote for intestinal worms. Source of hypercin which may counter the HIV virus.

St. John’s Wort Side Effects

As with any herbal remedy, it’s important to note that the medicinal use of St. John’s Wort should be approached with caution, and individuals considering its use should consult with a healthcare professional. Additionally, the quality and standardization of St. John’s Wort preparations can vary, so it’s important to use products from reputable sources.

Side effects reported from taking St. John’s wort by mouth include: Dizziness, Drowsiness, Dry mouth, Headache, Irritability, Upset stomach.

The herb may interact with various medications, affecting their efficacy, and may have side effects. Not to be taken together with the contraceptive pill, anti-epilepsy treatments and a number of other medications including anti-depressants. If you are taking any medication consult your doctor before starting St John’s Wort.

St. John’s Wort is an MAO inhibitor and should not be used with alcohol and some other foods. It should not be taken together with foods that contain tyramine i.e. cheese, red wine, preserved meats and yeast extracts.

Both oral and topical forms of St. John’s wort may make unprotected skin more sensitive to sunlight or artificial light in sun tanning parlors. Some evidence from case reports also seems to associate a higher risk of cataracts with possible eye sensitisation to light when St. John’s wort is taken. If you use St. John’s wort, be sure to use sunscreen and eye protection when exposed to sunlight or artificial light used in sun tanning.

Rare cases of serotonin syndrome, a potentially dangerous oversupply of serotonin in the body, have been attributed to taking St. John’s wort. Uncontrolled serotonin syndrome may result in coma, seizures, and death. Symptoms of serotonin syndrome include: Confusion, Euphoria, Fever, Hallucinations, Inability to coordinate muscles, Nausea, Restlessness, Shakiness, Sweating, Vomiting.

Do Not take St. John’s Wort if you are having Chemotherapy, or will be starting chemotherapy within several weeks, as St. John’s wort affects the metabolism (breakdown) of chemotherapy drugs by the liver and therefore seems to make these drugs much less effective.