Twenty-four studies were included in the review: 21 RCTs (n=2,175), 1 CCT (n=60) and 2 uncontrolled trials (n=86).
Effectiveness.
Black cohosh (4 RCTs, n=352; 1 CCT, n=60; 2 uncontrolled trials, n=86): all 7 studies reported a significant improvement in menopausal symptoms after 12 to 24 weeks compared with placebo. One RCT reported no significant difference between treatments in the frequency of hot flushes.
Red clover (4 RCTs, n=370): 1 RCT reported a significant reduction in the frequency of hot flushes compared with placebo; the other three reported no significant difference between red clover and placebo.
Soy isoflavonoids (9 RCTs, n=912): 5 RCTs reported a significant reduction in the frequency of hot flushes compared with placebo; the other four reported no significant difference between soy isoflavonoids and placebo.
Sage plus alfalfa (1 RCT, n=30): the RCT reported a significantly greater reduction in the frequency of hot flushes at 12 weeks compared with placebo.
Studies reported no significant difference in hot flushes between dong quai (1 RCT, n=71), evening primrose oil (1 RCT, n=56) or ginseng (1 RCT, n=384) versus placebo.
Safety.
The most common adverse effects reported were gastrointestinal (bloating, nausea and constipation). Studies reported no significant difference in adverse effects between placebo and black cohosh, dong quai, evening primrose oil, red clover, sage and soy (no details were reported). Adverse effects reported in studies not included in the efficacy review were also presented, but not in detail.