St. John’s Wort for Weight Control
Common name: Klamath weed
Botanical name: Hypericum perforatum
Why do dieters use it?*
Some dieters say that St. John’s wort
- helps improve energy and alertness.
- helps relieve stress and anxiety.
What do the advocates say?*
St. John’s wort is well established as a remedy for mild to moderate depression.
Since depression can lead to weight gain, and since medications with actions similar to that
of St. John’s wort have been used for weight loss, some people have proposed that St.
John’s wort can be useful for weight loss. However, no research at all has investigated
whether St. John’s wort has any value for this purpose.
How much is usually taken by dieters?
The standard recommendation for mild to moderate depression is 500 to 1,050 mg of St.
John’s wort extract per day.1 2 3 Length of use should
be discussed with a healthcare professional.
Are there any side effects or interactions?
St. John’s wort has a low incidence of side effects compared to prescription
antidepressants. An adverse events profile of St. John’s wort found that, of 14
controlled clinical trials, seven reported no adverse reactions, two had no information, and
five reported a total of seven mild reactions.4 Adverse effects reported included
stomach upset, fatigue, itching, sleep disturbance, and skin rash. The rate of adverse
reactions was always similar to that of the placebo. Additionally, in seven trials comparing
St. John’s wort with other antidepressants, the adverse reaction rate for St.
John’s wort was consistently lower than that of the antidepressant drugs with which it
was compared.
St. John’s wort can make the skin more sensitive to sunlight.5 Therefore,
fair-skinned people should be alert for any rashes or burns following exposure to the sun.
Three cases of severe blistering and burns were reported in people taking St. John’s
wort internally or applying it topically and then being exposed to sunlight.6 There
is a case report of a woman experiencing neuropathy (nerve injury and pain) in sun-exposed
skin areas after taking 500 mg of whole St. John’s wort for four weeks.7
Although St. John’s wort has photosensitizing properties, the severity of this reaction
is not typical for people taking the herb.
People with a history of manic-depressive illness (bipolar disorder) or a less severe condition known as
hypomania, should avoid use of St. John’s wort as it may trigger a manic
episode.8 9 10 11
There is a single case report in which ingestion of St. John's wort appeared to cause high blood pressure in a 56-year-old man. The
blood pressure returned to normal when the herb was discontinued.12
Are there any drug
interactions?
Certain medicines may interact with St. John’s wort. Refer to drug interactions for a list of those medicines.
Caution: It is likely that there are many drug interactions with St.
John's wort that have not yet been identified. St. John's wort stimulates a drug-metabolizing
enzyme (cytochrome P450 3A4) that metabolizes at least 50% of the drugs on the
market.13 Consequently, St. John's wort could potentially interfere with a large
number of medications. Individuals taking any medication should, therefore, consult with a
physician before taking St. John's wort.
Parts used and where grown
St. John’s wort is found in Europe and the United States. It is especially abundant
in northern California and southern Oregon. The above-ground (aerial) parts of the plant are
gathered during the flowering season.
*Dieters and weight-management advocates may claim benefits for St.
John’s wort based on their personal or professional experience. These are individual
opinions and testimonials that may or may not be supported by controlled clinical studies or
published scientific articles on St. John’s wort. For more complete and detailed
information, including references and safety information, see St. John's Wort as an herbal remedy .
References:1. Brown DJ. Herbal Prescriptions for Better Health. Rocklin,
CA: Prima Publishing, 1996, 159–65.
2. Woelk H. Comparison of St. John’s wort and imipramine for
treating depression: Randomized controlled trial. BMJ 2000;321:536–9.
3. Philipp M, Kohnen R, Hiller KO. Hypericum extract versus imipramine or
placebo in patients with moderate depression: randomized multicenter study of treatment for
eight weeks. BMJ 1999;319:1534–9.
4. Ernst E, Rand JI, Barnes J, et al. Adverse effects profile of the
herbal antidepressant St. John’s wort (Hypericum perforatum L.) Eur J Clin
Pharmacol 1998;54:589–94.
5. Brockmöller J, Reum T, Bauer S, et al. Hypericin and
pseudohypericin: Pharmacokinetics and effects on photosensitivity in humans.
Pharmacopsychiatry 1997;30(suppl):94–101.
6. Lane-Brown MM. Photosensitivity associated with herbal preparations of
St. John’s wort (Hypericum perforatum). MJA 2000;172:302[Letter].
7. Bove GM. Acute neuropathy after exposure to sun in a patient treated
with St John’s Wort. Lancet 1998;352:1121–2 [letter].
8. Nierenberg AA, Burt T, Matthews J, Weiss AP. Mania associated with St.
John’s wort. Biol Psychiatry 1999;46:1707–8.
9. Moses EL, Mallinger AG. St. John’s wort: Three cases of possible
mania induction. J Clin Psychopharmacol 2000;20:115–7.
10. O’Breasail AM, Argouarch S. Hypomania and St John’s wort.
Can J Psychiatry 1998;43:746–7 [letter].
11. Schneck C. St. John’s wort and hypomania. J Clin
Psychiatry 1998;59:689 [letter].
12. Zullino D, Borgeat F. Hypertension induced by St. John's Wort: a case
report. Pharmacopsychiatry. 2003;36:32.
13. Markowitz JS, Donovan JL, DeVane CL, et al. Effect of St John's wort
on drug metabolism by induction of cytochrome P450 3A4 enzyme. JAMA
2003;290:1500–4.