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Indications supported by clinical trials
Effectiveness
for treatment of menopausal symptoms: possible.
Multiple clinical studies of symptomatic menopausal
women have demonstrated significant reductions in symptoms with black
cohosh treatment.(23-32)
(5 open, uncontrolled designs, with 6 randomized, controlled or comparison
studies).(22) In some studies, black cohosh was as effective at reducing
these types of symptoms as estrogen compounds.(7) Additional studies of
black cohosh in combination with other dietary supplements ( St. John’s
Wort in one study,(7) green tea, Panax ginseng, soy extract, valerian,
kava, and hops in another), have shown similar degrees of efficacy.
Effectiveness for other gynecologic indications:
uncertain. No clinical
trials have looked specifically at the effectiveness of black cohosh in
treating PMS.(33) In addition, the herb’s use for dysmenorrhea, though
approved by the German Commission E, has not been confirmed by rigorous
clinical studies.(34)
Effectiveness for treating menstrual migraine: uncertain.
In one randomized, placebo-controlled study, Burke et al. evaluated the
effects of a combination of soy, dong quai, and black cohosh on migraine
frequency, duration, and intensity on days 2 to 3 of the menstrual cycle.(17)
The study revealed a small, but significant improvement in mean headache
severity scores in the treatment group.(17) Further studies are needed
to confirm this effect.
Effectiveness for enhancing the effects of tamoxifen for breast cancer:
uncertain.
Nesselhut found that supraphysiological concentrations
of black cohosh blocks estrogen stimulation of breast cancer cells in
vitro. When given with tamoxifen, the effects were greater than with either
substance alone.(7) However, these studies were not replicated with an
ER-negative cell line, raising the possibility of a non-specific, cytotoxic
effect. No clinical studies have yet been done.
Effectiveness for treating joint symptoms: uncertain.
One study, which looked at Rheumalex (Willow bark,
Guaiacum resin, Black Cohosh, Sarsaparilla, and Poplar bark) for pain
relief in patients with RA and OA showed small, but statistically significant
results with higher levels of improvement in the RA group.(35)
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