Annatto - Faslodex (Fulvestrant) Interaction
Herbal: Annatto
Also Known As: Bixa orellana, Acafrao, Acafroa, Achiote, Achioti, Achiotillo, Achote, Achote of the Mountain, Analto, Anatto, Annatto Orellana, Annato, Annotta, Arnotta, Atole, Axiote, Bicha, Bija, Bixa, Bijo, Bijol, Black Grain, Caituco, Cascaverde, Graopreto, Green Peel, Guajachote, Koessewee
Drug: Fulvestrant
Brand names:
Faslodex
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jun 22, 2025
Interaction Details
There were no interactions found between Fulvestrant and Annatto. This does not mean the potential for an interaction does not exist, however. There is often a lack of studies and data surrounding traditional medicine, especially concerning drug interactions, so it is important to always consult your provider before making any changes to your medication regimen.
Annatto Overview
Annatto is a natural food coloring made from the seeds of the achiote tree (Bixa orellana), which is native to Central and South America. The tree is known for its small, red, spiky seeds (annatto) which have a slightly sweet, earthy flavor and are sometimes used as a spice, but more commonly for their coloring properties. The seeds are ground into a powder and used to add a yellow or orange color to foods. It can also be used to dye fabrics and cosmetics.
Annatto has also been used in traditional medicine for a variety of purposes, including as a source of antioxidants, as an anti-infective, to increase athletic performance, to decrease muscle soreness, and improve bad breath.
There have been several reports of annatto causing allergic reactions in some individuals, so it should be used cautiously.
Fulvestrant Overview
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Fulvestrant injection is used alone or in combination with ribociclib (Kisqali®) to treat a certain type of hormone receptor positive, advanced breast cancer (breast cancer that depends on hormones such as estrogen to grow) or breast cancer has spread to other parts of the body in women who have experienced menopause (change of life; end of monthly menstrual periods) and have not previously been treated with an anti-estrogen medication such as tamoxifen (Nolvadex). Fulvestrant injection is also used alone or in combination with ribociclib (Kisqali®) to treat hormone receptor positive, advanced breast cancer or breast cancer that has spread to other parts of the body in women who have experienced menopause and whose breast cancer has worsened after they were treated with an anti-estrogen medication such as tamoxifen. Fulvestrant injection is also used in combination with palbociclib (Ibrance®) or abemaciclib (Verzenio®) to treat hormone receptor positive, advanced breast cancer in women whose breast cancer has spread to other parts of the body and has worsened after they were treated with anti-estrogen medication such as tamoxifen. Fulvestrant is in a class of medications called estrogen receptor antagonists. It works by blocking the action of estrogen on cancer cells. This can slow or stop the growth of some breast tumors that need estrogen to grow.
Annatto - More Interactions
Annatto interacts with 84 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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Dr. Brian Staiger, PharmD
In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!
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