St Johns Wort Side Effects|Cautions & Contraindications


It is generally believed that the adverse effects of herbal products are minimal and they are considered safer than medicines. However, we must keep in mind that the herbal products also have active agents and traditionally medicines have been derived from herbs.

Therefore herbal products may have some adverse effects and potential herb/drug interactions. The adverse effects of st johns wort are lesser than the tricyclic antidepressants and the SSRIs (Selective serotonin reuptake inhibitors). The common st johns wort side effects are:

✓ Nausea, bloating or vomiting

✓ Dizziness

✓ Confusion

✓ Drowsiness

✓ Dryness of mouth

✓ Increased urinary frequency

Common and some other side effects are as follows:

1. Gastrointestinal symptoms such as stomach upset, nausea, bloating or vomiting.


2. Dizziness and confusion can occur for a while.


3. You may feel tired and drowsy.


4. Skin Allergy may occur as a result of photosensitivity.

  • Photosensitivity was observed in patients taking oral st johns wort in the form of herbal tea or hypericum extract (240 mg) everyday for about three years. It was reversible and the patients recovered when the herbal treatment was stopped.

  • Skin lesions appeared in the areas exposed to the light but disappeared upon discontinuation of the herb. To decrease the chances of photosensitivity you can avoid direct sunlight exposure for 4-5 hours after the intake of the herbal preparation.

  • According to some anecdotal reports topical application of the hypericum extract can result in burns upon exposure to sun.

5. Dryness of mouth.


6. Frequency of urination may be increased.


7. Anorgasmia (Failure to experience an orgasm) may occur.


8. Swelling may occur at some body part.


Laboratory Study

It was observed in one laboratory study that high concentrations of st johns wort can badly effect the eggs (oocytes) and the sperms, therefore it may adversely affect the fertility in very high doses.


Interaction with Drugs


St johns wort can interact with other medicines therefore caution must be taken in the simultaneous use of other medicines. Always consult your physician if you are taking some medicine along with st johns wort. Researchers have found the interaction of st johns wort with the following medicines:


1. HIV 1 protease inhibitors particularly Imatinib and Indinavir.


2. Antifungal drugs especially voriconazole.


3. Cyclosporin, tacrolimus and other antirejection agents.


4. Benzodiazepines particularly quazepam.


5. Opioids especially methadone.


6. Histamine blockers especially fexofenadine.


7. Calcium channel blockers particularly verapamil.


8. Mycophenolic acid and


9. Simvastatin.

Contraindications/Cautions

The following cautions must be taken while using this herbal medicine.


1. It is contraindicated in pregnancy.


2. Extreme caution must be taken for simultaneous use with other antidepressants i.e MAO (monoamine oxidase inhibitors), TCA (Tricyclic antidepressants) and SSRIs (Selective serotonin reuptake inhibitors).

The concomitant use with other antidepressants may precipitate mania, hypomania or fatal serotonin syndrome. I would recommend taking St johns wort alone and NEVER combine it with an antidepressant. Most of the research studies have shown that its antidepressant properties can manage mild to moderate depression as a single agent therapy.


3. Caution must be taken in individuals taking reserpine.


4. In females taking oral contraceptive pills, it may decrease the levels of estrogen in the body.


5. It may cause an increase in Thyroid stimulating hormone.


Switching from antidepressant to st johns wort

If you have to switch from an antidepressant to st johns wort, a wash out period of at least 3 weeks must be observed before switching to the herbal product.


Discontinue before surgery

If you have to undergo any surgery, it is advisable to discontinue the herbal medicine at least 5 days before the operation due the potential of interaction with various drugs.

If you experience st johns wort side effects, you can discontinue the herb and consult your physician.



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