My pharmacist said do not take tamoxifen with grapefruit or calcium. He said the calcium tends to bind up with it (and other drugs) and makes them less available for your body.
call your pharmacist and ask him/her exactly what herbals will affect it.
Dear Ann, As more and more people are using various herbs and herbal products, we don't have alot of information about how and if these substances will interact with medications. A good practice is to make sure to keep your doctor informed of any over the counter medications, herbal products or nutritional supplements so if there is some known interaction you can know to avoid it. Another resource is to ask your pharmacist.
In regard to tamoxifen herbal preparations such as black cohosh, or **** quai are to be avoided in estrogen-dependent tumors (this is because of some of the estrogen like properties noted in these products).