Klamath weed

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St. John's wort (Hypericum perforatum)

(saynt jonz wort) ,


(trade name),

Demon chaser

(trade name),


(trade name),


(trade name),

Klamath weed

(trade name),

Rosin rose

(trade name),

Tipton weed

(trade name)


Therapeutic: antidepressants
Oral: Management of mild to moderate depression and obsessive compulsive disorder (OCD). (Not effective for major depression.) Topical: Inflammation of the skin, blunt injury, wounds and burnsOther uses are for capillary strengthening, decreasing uterine bleeding, and reducing tumor size


Derived from Hypericum perforatum; the active component is hypericin.
Oral: Antidepressant action my be due to ability to inhibit reuptake of serotonin and other neurotransmitters.
Topical: Anti-inflammatory, antifungal, antiviral, and antibacterial properties.

Therapeutic effects

Oral: Decreased signs and symptoms of depression.
Topical: Decreased inflammation of burns or other wounds.


Absorption: Unknown.
Distribution: Unknown.
Metabolism and Excretion: Unknown.
Half-life: Hypericum constituents—24.8–26.5 hr.

Time/action profile

PO10–14 dayswithin 4–6 wkunknown


Contraindicated in: Pregnancy, lactation, or children.
Use Cautiously in: History of phototoxicity; Surgery (discontinue 2 weeks prior to surgical procedures); Alzheimer's disease (may induce psychosis); Patients undergoing general anesthesia (may cause cardiovascular collapse); History of suicide attempt, severe depression, schizophrenia or bipolar disorder (can induce hypomania or psychosis).

Adverse Reactions/Side Effects

Central nervous system

  • dizziness
  • restlessness
  • sleep disturbances


  • hypertension


  • hypoglycemia


  • abdominal pain
  • bloating
  • diarrhea
  • dry mouth
  • feeling of fullness
  • flatulence
  • nausea
  • vomiting


  • neuropathy


  • allergic skin reactions (hives, itching, skin rash)
  • phototoxicity


  • serotonin syndrome


Concurrent use with alcohol or other antidepressants (including SSRIs and MAO inhibitors ) may ↑ risk of adverse CNS reactions.May ↓ the effectiveness and serum concentrations of digoxinalprazolamamitriptylineimatinibirinotecanwarfarin andprotease inhibitors.Use with MAO Inhibitorstramadolpentazocine and selective serotonin agonists could result in serotonin syndrome.May ↓ effectiveness of oral contraceptives.May ↓ plasma cyclosporine and tacrolimus levels by 30–70% and cause acute transplant rejection.May ↑ metabolism of phenytoin and phenobarbital and cause loss of seizure control.Avoid use of St. John’s Wort and MAO Inhibitors within 2 wk of each other.May ↑ risk of serotonin syndrome when taken with tryptophanand SAM-e.
Oral (Adults) Mild Depression—300 mg of St. John’s Wort (standardized to 0.3% hypericin) 3 times daily or 250 mg twice daily of 0.2% hypericin extract. OCD—450 mg twice daily of extended release preparation.
Topical (Adults) 0.2–1 mg total hypericin daily.


Preparations for Oral Use

Dried herb: OTC
Dried (hydroalcoholic) extract: OTC
Oil: OTC
Tincture: OTC

Preparations for Topical Application

Liquid: OTC
Semisolid: OTC

Nursing implications

Nursing assessment

  • Depression: Assess patient for depression periodically during therapy.
  • Inflammation: Assess skin or skin lesions periodically during therapy.

Potential Nursing Diagnoses

Ineffective coping (Indications)
Anxiety (Indications)
Deficient knowledge, related to medication regimen (Patient/Family Teaching)


  • Oral: Tea can be prepared by mixing 2-4 dried herb in 150 mL of boiling water and steeping for 10 min.

Patient/Family Teaching

  • Instruct patient to take St. John’s wort as directed.
  • Patients with depression should be evaluated by health care professional. Standard therapy may be of greater benefit for moderate to severe depression.
  • Advise patient to notify health care professional of medication regimen prior to treatment or surgery.
  • Caution patients to avoid sun exposure and use protective sunscreen to reduce the risk of photosensitivity reactions.
  • Inform patient to purchase herbs from a reputable source and that products and their contents vary among different manufacturers.
  • Caution patient not to use alcohol while taking St. John’s wort.
  • Warn patients that St. John’s Wort may reduce the therapeutic effectiveness of several drugs.
  • May potentiate effect of sedatives and side effects of other antidepressants. Do not take within 2 wk of MAO Inhibitor therapy.
  • Instruct patient to consult healthcare professional before taking otherRx, OTC, or herbal products concurrently with St. John’s wort.
  • Inform patient that St. John’s wort is usually taken for a period of 4–6 wk. If no improvement is seen, another therapy should be considered.

Evaluation/Desired Outcomes

  • Decrease in signs and symptoms of depression or anxiety.
  • Improvement in skin inflammation.
Drug Guide, © 2015 Farlex and Partners

Saint John’s wort

Fringe medicine
An essence which, in the pseudoscience of flower essence therapy, is said to provide a sense of consciousness, self-awareness and inner strength. 

Herbal medicine
A perennial herb containing flavonoids, glycosides, mucilage, tannins and volatile oil, which is antibacterial, anti-inflammatory, antimicrobial, astringent, expectorant and sedative; it has been used internally for arthritis, bed-wetting, bronchitis, colds, mental disorders (anxiety, depression, insomnia, nervousness), menstrual cramps, neuralgia, rheumatic pain and sciatica, and topically for burns, cuts and wounds. It was used transiently as a herbal therapy for AIDS.
St John’s wort has been deemed unsafe by the FDA, given its phototoxicity; it causes hypertension, headaches, nausea, and vomiting; it may interact with amphetamines, amino acids (tryptophan, tyrosine), anti-asthmatic inhalants, beer, wine, chocolate, coffee, fava beans, cold and hay fever medication, narcotics, nasal decongestants and smoked or pickled foods.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
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