Is black cohosh a good remedy for hot flashes due to menopause? Any concerns? Does it increase weight?

Debatable . Black cohosh is used by some to combat hot flashes and insomnia related to menopausal decline. It's mechanism of action is unknown. It was once thought that it had estrogenic effects, but that has since been shown not to be the case. Estrogenic effects could lead to weight gain, but since it doesn't act this way weight gain should not be an issue.