Can I take Biotin and Tamoxifen together?

Why this happens

Biotin does not change how tamoxifen is absorbed, broken down, or used by the body. However, biotin is often used in laboratory testing technology. Taking high doses of biotin can cause 'false' results in hormone tests (like oestrogen or thyroid tests) and tumour marker tests, which your doctor may use to monitor your treatment.

What you should do

It is generally safe to take these together. However, you must tell your doctor and the laboratory staff that you are taking biotin before having any blood tests. Most experts recommend stopping biotin supplements at least 48 to 72 hours before a blood test to ensure the results are accurate.

Important precautions

Laboratory blood tests (e.g. thyroid or heart attack tests)

Biotin can significantly interfere with laboratory blood tests, leading to false results. You must stop taking biotin at least 48 hours before having any blood work and inform your doctor you are taking it.

Blood clots (Thrombosis)

Tamoxifen significantly increases your risk of serious blood clots in the legs or lungs. Seek immediate medical help if you experience sudden shortness of breath, chest pain, or a painful, swollen calf.

Uterine (womb) cancer

Tamoxifen can increase the risk of changes to the lining of the womb, including cancer. You must report any unusual vaginal bleeding, spotting, or changes in vaginal discharge to your doctor immediately.

Food and drink warnings

Grapefruit and grapefruit juice

Grapefruit can interfere with how your body processes tamoxifen, potentially making the medicine less effective. It is best to avoid consuming grapefruit products while taking this medication.

Alcohol

While there is no direct chemical interaction, alcohol can worsen certain side effects of tamoxifen, such as hot flushes. Additionally, heavy drinking can impact liver health, which is important since tamoxifen is processed by the liver. Moderate consumption is usually acceptable, but check with your doctor.

Raw egg whites

Consuming large amounts of raw egg whites over a long period can prevent your body from absorbing biotin. This is because raw egg whites contain a protein called avidin that binds to biotin. Cooked eggs do not cause this issue.

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.