St. John’s Wort
Don St. John, P.A.
Adult Outpatient Psychiatry
University of Iowa Department of Psychiatry

Peer Review Status: Internally Peer Reviewed
Creation Date: June 1998
Last Revision Date: January 31, 2000

St. John’s Wort

St.John’s wort is used to treat mild to moderate depression and possibly anxiety.

This medication is not recommended for treatment of severe depression,
including depression with suicidal thoughts, psychotic features (hallucinations,
confused thoughts), or melancholia (weight loss, early morning awakening, very low energy).

Proper use of this medication:

  • There is little information available on this medication in the English
  • Because over-the-counter herbal medications are not regulated in this country,
    the purity and potency of any given brand may vary.
  • There is no medical research concerning the method of changing from prescription
    antidepressants to St.John’s Wort.
  • Consult with your physician before discontinuing any medication you are
    currently taking.
  • Do not start taking St.John’s Wort until you have been off your current
    antidepressant at least one week (2 weeks if you are taking Nardil/phenelzine
    or Parnate/tranylcypromine).
  • The commonly reported dose of extract is 300 – 1000 mg per day. (Most people
    take 300 mg, 3 times daily.)
  • The commonly reported dose of hypericin is 0.4 – 2.7 mg per day.
  • This medication is not addictive, and does not cause a high feeling.
  • When taken regularly, this medication may require 4-8 weeks before the full
    effects are noticed.
  • Do not drink alcohol while taking this medication.
  • If there is a possibility you may become pregnant or breast-feed while on
    this medication, first consult with your psychiatrist. This drug has not been
    tested in pregnancy, and it is unknown if it is excreted in breast milk.
  • This medication should not be abruptly discontinued.
  • Store this medication in a cool, safe place away from the reach of children.

Most studies show no difference in side effects between St.John’s
wort and placebo. However reported possible side effects include:

  • Anxiety/restlessness: This will usually go away with continued use.
  • Fatigue: This is uncommon and usually goes away with continued use.
  • Concentration: Some studies demonstrate improved concentration and attention.
  • Dizziness: This is uncommon and usually goes away with continued use.
  • Nausea: Take this medication with food. This usually goes away with continued
  • Weight loss, loss of appetite: This is uncommon and usually goes away with
    continued use.
  • Diarrhea or constipation: High-fiber diet and regular exercise may treat
    this uncommon side effect.
  • Sun sensitivity: This is a common side effect in animals ingesting St.John’s
    Wort, but has been uncommonly reported in humans, as rash or skin pain. Use
    sunscreen and wear appropriate protective clothing. The effect is temporary,
    ending soon after the drug is discontinued.
  • Allergic reactions: Have been reported in .5% of patients, and include skin
    rash and itching.
  • If any side effect persists or becomes intolerable, discuss this with your

Though there have been no significant drug interactions reported in the
literature, the following other medications may require dosage adjustment while
taking St.John’s Wort:

  • Monoamine Oxidase Inhibitors (Tranylcypromine/Parnate, Phenelzine/Nardil,
  • Serotonin Reuptake Inhibitors (Paroxetine/Paxil, Sertraline/Zoloft, Fluvoxamine/Luvox,
  • Warfarin/Coumadin.
  • Cyclic Antidepressants (Amitriptyline/Elavil, Nortriptyline/Pamelor, Protriptyline/Vivactil,
    Clomipramine/Anafranil, Imipramine/Tofranil, Desipramine/Norpramin, Trimipramine/Surmontil,
    Amoxapine/Asendin, Doxepin/Adapin/Sinequan, Maprotiline/Ludiomil, Trazodone).
  • Drugs that may cause sun sensitivity, such as Tetracycline and many anti-psychotic

St.John’s Wort contains hypericin, which inhibits monoamine oxidase, a chemical
associated with depression. These could lead to serious interactions with foods
containing tyramine, alcohol, narcotics, and over-the-counter decongestants.
Foods containing tyramine include: Yeast, sour cream, aged or canned meats,
liver, meat extracts, salami, sausage, aged cheeses (blue, brick, Brie, Camembert,
cheddar, Colby, Emmenthaler, Gouda, Mozzarella, Parmesan, provolone), dried
fish, herring, broad beans, eggplant.

Further information may be obtained from: