St. John's Wort: Drug Interactions With Antidepressants?

St. John's Wort Drug Interactions With Antidepressants
St. John's Wort. esemelwe/Getty Images

Question: Does St. John's wort have any drug interactions with antidepressants?

Answer:  Yes, St. John's wort has the potential to interact with several different types of antidepressant drugs, including:

  • Selective serotonin reuptake inhibitors (SSRIs) - for example, fluoxetine (Prozac) and paroxetine (Paxil)
  • Tricyclics - for example, amitriptyline (Elavil) and imipramine (Tofranil)
  • Monoamine oxidase inhibitors (MAOIs) - for example, tranylcypromine (Parnate) and phenelzine (Nardil)

    Since St. John's wort is able to increase the amount of serotonin in the brain, just like prescription antidepressants do, when it's taken in combination with one of these drugs, it's possible that serotonin could build up to a dangerous level. This condition is called serotonin syndrome.

    Serotonin syndrome can cause some very serious symptoms, such as:

    • Confusion
    • Hypomania
    • Agitatiion
    • Headache
    • Coma
    • Shivering
    • Sweating
    • Fever
    • High Blood pressure
    • Rapid heartbeat
    • Irregular heartbeat
    • Upset stomach
    • Diarrhea
    • Involuntary twitching
    • Muscle rigidity
    • Seizures
    • Overactive reflexes
    • Tremor
    • Loss of consciousness

    Serotonin syndrome has the potential to be fatal if not treated immediately so it is very important to seek out medical assistance in a timely manner if you or someone else are having these symptoms.

    The treatment for serontonin syndrome involves stopping the medications that are causing it and treating the symptoms until the condition resolves itself.

      The administration of serotonin antagonists like methysergide or cyproheptadine can be helpful and benzodiazepines may also be given in order to relieve muscle rigidity.  In some cases, it may be necessary to apply mechanical ventilation to aid with breathing.  Usually it takes from about 24 hours for the symptoms to subside, although it could take as long as 96 hours.

    In order to avoid serotonin syndrome, it is best to always follow your doctor's advice about dosing your medications.  In addition, you notify him of any other medications that you are taking, including over-the-counter herbal preparations like St. John's wort.  Finally, you should seek your doctor's advice about how to properly transition from one antidepressant to another or from a prescription antidepressant to herbs or supplements which might potentially affect serotonin.  It is possible that your serotonin levels could remain elevated for a period of time after you stop taking your medication so it is advisable to allow a washout period before starting another medication, herb or supplement which may have similar effects on serotonin.


    Ehrlich, Steven D.  "Possible Interactions With:  St. John's Wort."  University of Maryland Medical Center.  University of Maryland Medical Center.  Last reviewed:  May 13, 2007.  Accessed:  September 6, 2015.

    Mayo Clinic Staff.  "Serotonin Syndrome."  Mayo Clinic.  Mayo Foundation for Medical Education and Research.  Last updated:  March 13, 2014.  Accessed:  September 6, 2015.

    "Serotonin Syndrome."  Family Practice Notebook.  Family Practice Notebook, LLC.  Accessed:  September 6, 2015.

    "St. John's Wort."  WebMD.  WebMD, LLC.  Accesssed:  September 6, 2015.

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