Disclaimer

Although we take care to ensure accuracy, Macmillan Cancer Support does not accept liability for the information and materials provided or referenced in Ask an Expert or for any errors or omissions in them, or for third-party information or services such as other websites we may link to. The information and materials provided or referenced in Ask an Expert are for information purposes only and are not intended to be legal, financial or medical advice or opinions. If you need more details on your rights, please contact a financial, legal or other appropriate adviser.

We recommend that you consult your doctor if you are concerned about your health. Any You should not rely on any information and materials provided or referenced in Ask an Expert including by our Experts as they are not a replacement for advice, diagnosis or treatment from your medical team, and our Experts cannot provide a second opinion to that of your medical team.

Your question can be read by others – so please don't post your contact details or any other information that could personally identify you. Please read our Terms and Conditions and Community Guidelines for more details.

Letrozole and fluoxetine

H.Anderson
  • 1 reply
  • 40 subscribers
  • 1388 views

I’ve just read something online which flagged up a possible concern with taking these two meds together. I have been on both for nearly five years and hadn’t been warned about this before. Do I need to worry.

thanks

  • Hello H.Anderson,

    Thank you for getting in touch with us, and welcome to our online community. My name is Annerose I’m one of the Cancer Information Nurses here at the Macmillan Cancer Support line.

    Fluoxetine can have a negative effect on how Tamoxifen works, but there is nothing reported about any interactions with Letrozole.

    We understand how a report you saw online can cause you some concerns, as both Letrozole and Tamoxifen are given as anti-oestrogen therapies.

    However, the way they actively work is different, and therefore Fluoxetine is ok to take with Letrozole but must be avoided when taking Tamoxifen.

    You have been taking Letrozole and Fluoxetine for nearly 5 years, and your team will be well aware of any contra-indications or undesired interactions between those two medications and would have made necessary changes or adjustments.

    You can mention this to your team when you see or speak to them next and discuss your concerns, for further reassurance and peace of mind.

    I hope this has been helpful, but please don’t hesitate to get back in touch if you need any further information or support.

    Best wishes and take care 

    Annerose (Cancer Information Nurse Specialist) 

    You can also speak with the Macmillan Support Line team of experts. Phone free on 0808 808 0000 (7 days a week, 8am-8pm) or send us an email. 

    Ref/ GG

Help us do whatever it takes, because we’ve never been needed more.

© Macmillan Cancer Support 2025 © Macmillan Cancer Support, registered charity in England and Wales (261017), Scotland (SC039907) and the Isle of Man (604). Also operating in Northern Ireland. A company limited by guarantee, registered in England and Wales company number 2400969. Isle of Man company number 4694F. Registered office: 3rd Floor, Bronze Building, The Forge, 105 Sumner Street, London, SE1 9HZ. VAT no: 668265007