Medicines, foods and supplements to avoid on anastrozole

Anastrozole works by keeping the amount of oestrogen in your body very low, so the most important things to avoid are medicines and products that put oestrogen back. That means hormone replacement therapy, combined contraceptive pills, tibolone and most oestrogen creams or pessaries should not be used unless your oncologist has specifically agreed. Tamoxifen should not be taken at the same time as anastrozole either: a large trial found the two together worked less well than anastrozole alone, so they are only ever used one after the other. Beyond that, anastrozole has relatively few important interactions with everyday medicines. Paracetamol, most blood pressure and diabetes tablets, thyroid tablets, cholesterol medicines, calcium, vitamin D and bone-strengthening treatments can usually be taken alongside it. Common painkillers such as ibuprofen are not known to interact, although they carry their own risks for the stomach and kidneys with long use. Herbal remedies and supplements are the grey area. Some, such as red clover, dong quai and concentrated soy or isoflavone capsules, may act a little like oestrogen, and many Ayurvedic, Unani or homeopathic products do not list every ingredient, so it is safest to check each one with your team. Ordinary foods are different. Soy foods, dal, turmeric in cooking and normal amounts of tea and coffee are fine. Grapefruit is not known to affect anastrozole. Always tell every doctor, dentist and pharmacist that you take it.

Oestrogen is the key thing to avoid

Anything that adds oestrogen can work against anastrozole.

Most daily medicines are fine

Few common prescriptions interact, but a quick check is still worthwhile.

Supplements need checking

Herbal and plant-based products are the most common source of doubt.

Interaction advice is a mix of firm evidence and sensible caution. It helps to know which is which.

Oestrogen advice is firm

The case against adding oestrogen during treatment, and against combining tamoxifen with anastrozole, rests on good evidence.

Supplement advice is cautious

Few herbal products have been properly tested with anastrozole. Advice to avoid them is based on how they might work, not on proof of harm.

Food worries are often overstated

Studies suggest soy foods eaten as part of a normal diet do not raise the risk of breast cancer returning. The concern is mainly with concentrated capsules.

What this page cannot tell you

It cannot check your own medicines. Your pharmacist or oncologist can review your full list.

Anastrozole is taken for years, and during that time you will likely see other doctors. A short mention avoids problems.

Gynaecologists and family doctors

They may otherwise suggest hormone treatment for menopause symptoms or bleeding without knowing your history.

Dentists and surgeons

Anastrozole does not usually need stopping for dental work or surgery. Mention it, especially if you also receive a bone-strengthening injection.

Pharmacists and shop counters

Before buying any tonic, supplement or cream over the counter, say you are on anastrozole for breast cancer and ask whether it contains hormones.