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St. John’s Wort


St. John’s Wort is an herb that is extracted from the flowers and leaves of a shrub that has yellow-coloured flowers.

St. John’s Wort is originated from Europe. However, St. John’s Wort is now commonly found in Australia as the country produces 20 percents of world supply.

The usage of St. John’s Wort started since the ages of ancient Greek. Hippocrates has stated the usage of St. John’s Wort’s flower in the medicinal field. St. John’s Wort is given such name because the flowering season of this herb is approximately on the 24th of June, which is on the birthday of John The Baptis, whereas the word ‘wort’ is an old English word for ‘plant’.

Active Ingredient

Researchers have found a type of chemical in St. John’s Wort known as hypericin and it is effective in treating depression. Lately, research has revealed that another chemical named hyperforin plays a greater role in the treatment of depression.


St. John’s Wort is usually used as a herbal treatment for mild to moderate depression. It helps to alleviate symptoms associated with depression such as anxiety, fatigue, loss of appetite, and sleep disturbances.

How Does It Work

Natural Medicines Comprehensive Database has evaluated the effectiveness of St John’s Wort based on scientific evidence. It was shown that both hypericin and hyperforin that are contained in St. John’s Wort act as chemical messengers in the nervous system to regulate mood.

However, due to its many drug-drug interactions, St. John’s Wort is not the main choice in depression treatment especially for patients that are on other types of medicines.


St. John’s Wort is prepared in capsule form and to be swallowed whole. Topical use is not encouraged as it may cause serious side effects.

The dose as according to scientific researches for treatment of mild to moderate depression are as follows:

  1. When using St. John’s Wort with 0.3 % hypericin standard extract : 300 mg three times a day.
  2. When using St. John’s Wort with 0.2 % hypericin standard extract : 250 mg two times a day.
  3. When using St. John’s Wort with 5% hyperforin standard extract : 300 mg three times a day.
  4. For children under 12 years old with depression symptoms, when using St. John’s Wort with 0.3 % hypericin standard extract : 300 mg everyday.

When to take

St. John’s Wort should be taken after meal at the same time everyday to get optimal effects.

Duration of treatment

St. John’s Wort is only used for short term treatment. If the patient experiences any side effects or does not show any improvement, it is advisable to stop the treatment immediately. Long-term consumption should only be considered upon advices from doctor or pharmacist.

However, St. John’s Wort can not be stopped abruptly for individuals that have been taking it for long duration. It may cause unwanted side effects. Therefore, it should be tapered slowly.


Drug interaction occurs when the medicine reacts with another substance and causes unwanted effects. These interaction can either cause the medicine to be less effective or even harm the patients.

  1. Any interaction with herbs and supplements?

    No known interactions with herbs and supplements.

  2. Any interaction with food?

    No known interactions with food.

  3. Any interaction with medicine?

    St. John’s Wort may have interaction with the following medicines:

    • Warfarin
    • Ciclosporin
    • Theophylline
    • Oral contraceptive
    • Amitriptyline
    • Nortriptyline
    • Digoxin
    • Carbamazepine

rug Control Authority has decided that products containing St. John’s Wort should include warning on the packaging as below :

  • “This product may have interaction with other medicines. Please refer to doctor or pharmacist before using this product.”

Side effects that may occur

St. John’s Wort may be safe for most individual who are taking it for short-term. However, there are a few side effects that may occur such as :

  1. Sleep disturbances
  2. Nightmares
  3. Restless
  4. Anxious
  5. Easily irritated
  6. Stomachache
  7. Tired
  8. Dry mouth
  9. Dizzy
  10. Headache
  11. Skin rashes
  12. Diarrhea
  13. Throbbing pain

Special Precautions

Patient who are having any of the following conditions should consult the doctor before taking St. John’s Wort if the patient is having any of these conditions:

  1. Pregnant or breastfeeding

    Pregnant and breastfeeding: Safety of St John’s Wort during pregnancy is not proven. Breastfeeding mothers who consume St. John’s Wort may experience stomachache, sleepiness and fatigue. Due to lack of evidence, it is not recommended to use St. John’s Wort in pregnant or breastfeeding mother.

  2. Attention deficit-hyperactivity disorder (ADHD)

    Attention deficit-hyperactivity disorder (ADHD): Although St. John’s Wort is sometimes used for treatment of ADHD, it may also worsen the symptoms of ADHD, especially in those taking methylphenidate.

  3. Infertility

    Infertility: There are a few concerns that St. John’s Wort may interfere with conception. If you are trying to conceive and have a known fertility problem, it is advisable not to take St. John’s Wort.

  4. Bipolar disorder

    Bipolar disorder: St John’s Wort may cause mania in certain individuals and may also shorten the cycle between depression and mania.

  5. Major depression

    Major depression: St John’s Wort may lead to maniac symptoms with excessive physical activities and impulsive behaviours.

  6. Schizophrenia

    Schizophrenia: St John’s Wort may lead to psychosis in certain individuals who are schizophrenic.

  7. Anesthesia and surgery

    Anesthesia and surgery: The use of anesthesia during surgery in individuals that have been using St. John’s Wort for past six months may lead to serious heart complications.Therefore, it is advisable to stop using St. John’s Wort for at least two weeks before the scheduled surgery.

  8. Alzheimer’s disease

    Alzheimer’s disease: St. John’s Wort may contribute to dementia for individuals with Alzheimer’s disease.

Medicine storage

Products of St. John’s Wort should be stored in amber bottles and kept at room temperature, less than 30ºC. The active ingredient in St. John’s Wort will be deactivated when exposed to direct sunlight. Therefore, it should be stored in amber bottle.

Note : Information provided in the article is only a summary of the product and serve as reference of information. This article does not guarantee the safety and effectiveness of the product, nor the suitability for your conditions. This is not a personal health advice and does not substitute any professional health advice. Please refer to your doctor or pharmacist for more information before using this product.

Last Reviewed : 20 March 2015
Writer: : Kobu a/l Thiruvanackan
Translator: : Hazlin bt. Othman
Accreditor: : Munira bt. Muhammad