Medicines, foods and supplements to avoid on fulvestrant

Compared with many cancer medicines, fulvestrant has few known interactions. It is broken down in the liver, but studies have not shown that common medicines which speed up or slow down liver enzymes change its levels enough to matter. That is reassuring, but it does not mean anything goes. There are several things to be careful about. First, anything that adds oestrogen to the body, such as hormone replacement therapy, the combined contraceptive pill or high-dose plant oestrogen supplements, could work against the treatment. Second, because fulvestrant is injected deep into the buttock muscles, blood-thinning medicines and anything else that raises bleeding risk make bruising and bleeding at the injection site more likely. Third, fulvestrant is very often given with a partner tablet, such as palbociclib, ribociclib, abemaciclib, alpelisib or capivasertib, and these tablets do have important interactions with grapefruit, St John's wort and many prescription medicines. Fourth, fulvestrant can make some oestrogen blood tests read falsely high. Ordinary Indian food, including soy, dal, turmeric and spices in cooking amounts, is generally fine. The safest habit is to keep one updated list of everything you take and show it to your oncologist or pharmacist before starting anything new.

Fulvestrant itself is fairly simple

Few medicines change fulvestrant levels, so most everyday prescriptions can continue.

Partner tablets need more care

If you take a targeted tablet too, its interactions are usually the bigger concern.

Oestrogen and bleeding are the key themes

Avoid adding oestrogen, and tell your team about anything that affects clotting.

Interaction information is useful, but it has gaps, especially for traditional and herbal products.

Many products are untested

Most herbal and Ayurvedic products have never been studied with fulvestrant. No evidence of harm is not the same as proof of safety.

Product quality varies

Some remedies contain undeclared ingredients or vary between batches, which makes advice harder.

Lists are never complete

New medicines and new evidence appear all the time, so checks need repeating when things change.

What this page cannot tell you

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

A few simple habits prevent most problems.

Keep one list

Include prescriptions, over-the-counter medicines, vitamins, herbal products and home remedies.

Tell every doctor

Dentists, family doctors and specialists should know you are on fulvestrant and any partner tablet.

Mention it for blood tests

If oestrogen levels are being checked, remind the doctor that fulvestrant can affect the result.

Ask before surgery

For operations or dental work, your team may review blood thinners and injection timing together.