Don't use black cohosh for more than 6 months. Black cohosh contains salicylic acid. Use it with caution if you are also taking salicylate medicines such as aspirin. Black cohosh should not be used during pregnancy. In large doses it may cause premature birth.
Some natural remedies have the same effects as prescription medicines.
This means there is a danger of being overmedicated. If you have any unusual effects while taking any natural remedy, get advice from a doctor right away. Natural remedies and prescription medicines may interact. Lack of standardization may result in products with different strengths and effects. Lack of quality control may allow contamination of products.