Re. Tamoxifen and grapefruit etc

Hi, have just heard that when on Tamoxifen you should avoid Graprefruit and Pomegranate as these can interfere with the action of the drug. There is no mention of this in the instructions you get with the pills nor has my onc said anything ao I was unaware of this and have been merrily eating both the above. Can anyone advise? I have been on Tamoxifen for nearly 2 weeks now.

hi Haughtaj
I’ve been on tamoxifen for 5 years and consumed vast quantities of pomegranetes but not one grapefruit. I’ve never seen anything about either interfering with the drug. Nor has anyone said anything about avoiding them.
Sometimes I think we worry too much.
Life without pomegranetes in Autumn would be miserable.
Love Chinook

Hi - I don’t know about Pomegranate, but grapefruit can certainly interfere with the way the body metabolised drugs. It can both increase and decrease the effectiveness of drugs. This link suggests grapefruit increases the effectiveness of Tamoxifen, but should be avoided because it could result in increased side-effects. I can’t vouch for the accuracy of this information, but of it is correct it isn’t likely to have done you any harm for the last 2 weeks, unless you have had severe side effects. It might be a good idea to ask your pharmacist.

finty x

Thanks Finty, I always knew that grapefruit can interfere with some drugs but there is always a warning in the instructions. There is nothing in the tamoxifen instructions about avoiding any foods or alcohol and it was just by chance that I came across it.

hi also seville oranges, i dont know where that one came from.x

Hi haughtaj

Please feel free to call our helpline for further information about your query, the line is open 9-5 weekdays and 9-2 Sat on 0808 800 6000

Take care

Hi everyone

Posting this on behalf of the Breast Cancer Care nursing team:

"Hello everyone

Just noticed your query about a possible interaction between tamoxifen and grapefruit.

Haughtaj is right in saying that nothing is mentioned on the patient information sheet that is enclosed with the medication regarding this interaction.

Grapefruit can change the metabolism of a number of medications, and this has been well documented. Its action means that it is able to increase/decrease their effectiveness, depending on how much is taken and in which form. However, tamoxifen interaction has not been reported.

Pomegranates and oranges are also not reported to have interactions with tamoxifen.

If you have any concerns, the best people to talk to are your specialist team."

Breast Cancer Care nursing team

A friend was told by the pharmacist at the Marsden not to take the Penny Brohn supplements as they contain vit c and this adversly affected the tamoxifen she was taking. I guess the grapefruit is linked to that.

The other thing with adverse effects on tamixifen which is not on the patient info (but has been backed up my oncologist after I kept asking about it) is taking an ssri drug. My onc says it speeds up how quickly the liver processes the tamoxifen so it makes it SLIGHTLY less effective. it’s always a balancing exercise as for me to stop the ssri was more of a risk (of plunging back into depression) than the slightly less effective tamoxifen.

Does grapefruit have any impact on aromatase inhibitors ?

Lemongrove - this link showed the Tamoxifen / grapefruit warning but doesn’t say anything under the AI’s that I checked.

Hi Lemongrove

If you would like to talk this through and have some information on your question please do give the helpline a call on 0808 800 6000. The lines are open Monday to Friday 9 to 5pm and Saturday.

I hope this helps.

Best wishes Sam, BCC Facilitator

Seville’s have the same chemical found in grapefruit as do pomegranate and bergamot not sure about whether this chemical interferes with tamoxifen though. It can interfere with some chemo drugs