Preferably from manufacturers who have been around for a long time such as Schiff, Rexall, to name a few. Compare the Latin names to be sure which herb you're buying. Also, purchase herbs that indicate the percentage of active ingredients, and look for other chemicals that may have been used in the preparation. Rely on medical research, not package claims. It is commonly used in Germany in the drug Remifemin, and it is also available in the United States.
Black cohosh is available in pills, liquids, and extracts.
Short-term side effects include dizziness, diarrhea, and nausea. Black cohosh produces endometrial stimulation and may cause vaginal bleeding. Because of the possible estrogenic action, it should be used with caution after six months. The recommended dosage is 10 to15 drops, or three to four capsules per day. The long-term side effects are unknown.