Supplements during chemotherapy: what to check with your oncology team

CANCER SUPPORT · 7 MIN READ

upplements, herbs and teas can change how treatment works in the body. Before you start, stop or continue anything, here is what to check, and who to check it with.

In short

• Supplements, herbs and teas can change how treatment is cleared from the body.

• List everything you take, including teas, powders and anything bought online, and review it whenever treatment changes.

• Ask your oncology team or pharmacist before starting, stopping or continuing anything.

Supplements during chemotherapy are one of the most common questions people bring to an appointment, and one of the least discussed. Many people start something after a friend's recommendation or a late-night search, and are not sure whether to mention it.

Mention it. Everything you take matters during treatment, including things that feel too ordinary to count.

Why supplements matter during treatment

Many treatments are cleared by the liver and kidneys, through the same pathways that process food, herbs and supplements. When two things share a pathway, one can change how much of the other stays in the body. That can make treatment stronger than intended, or weaker.

Some interactions are well known. St John's wort, for example, speeds up how the liver clears many medicines, and grapefruit can slow it. Others are less certain, which is exactly why your team needs the full picture.

What counts as a supplement?

More than most people think. When you list what you take, include:

• vitamins, minerals and fish oil

• protein powders and greens powders

• herbal medicines, tinctures and capsules

• herbal and medicinal teas, including blends

• medicinal mushrooms

• homeopathic remedies

• anything bought online or overseas

• anything a friend or family member has given you

When is the timing important?

Some supplements may be fine between cycles but not on treatment days, or fine with one treatment and not another. Surgery, radiotherapy, chemotherapy, immunotherapy and hormone therapy each raise different questions. This is why a list checked once at the start of treatment is not enough. Review it whenever the treatment changes.

What about antioxidants?

Antioxidant supplements are one of the most debated questions in cancer care. Some treatments work partly by creating oxidative stress, and researchers are still studying whether high-dose antioxidant supplements interfere. The answer depends on the treatment, the dose and the timing. Food sources, such as vegetables and fruit, are a different matter from concentrated supplements. Ask your team before taking high-dose antioxidants during treatment.

Questions to ask your oncology team

• Here is everything I take. Is any of it a concern with my treatment?

• Should I stop anything before treatment days, and for how long?

• Is there anything I should stop before surgery?

• Does my treatment change how my liver or kidneys clear medicines?

• If my treatment changes, should we review this list again?

• Who on the team should I ask about supplements: my oncologist, my oncology nurse or the pharmacist?

How to make it easy

Write one list, with the name, the brand, the dose and how often you take it. Take photos of the labels. Bring the list to every appointment, and ask the oncology pharmacist to keep a copy on your file.

How I work alongside your oncology team

In consultation, I review everything you take, flag anything that needs checking, and give you a written list to bring to your team.

Where support is appropriate, it is matched to your treatment stage and timed around treatment days.

Frequently asked questions

Can I take supplements during chemotherapy? Some may be fine and others may interact with treatment. It depends on the treatment, the dose and the timing, so always check with your oncology team or pharmacist first.

Should I stop supplements before surgery? Some supplements and herbs affect bleeding or anaesthesia. Ask your surgical team which to stop and how far ahead.

Who should I ask about supplements during treatment? Your oncologist, oncology nurse or oncology pharmacist. A naturopath working alongside your team can help you prepare a clear list.

Where to start

If you are in treatment, or about to begin, an initial consultation is a calm place to bring everything you take and everything you have read. I review it all together, and put it in writing for your oncology team. Consultations are online, consult by consult, at whatever pace suits you.

This article is general education. In consultation, everything is coordinated with your oncology team.