Ssri and Tamoxifen: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Ssri and Tamoxifen unless specifically directed by your doctor.
How Ssri interacts with Tamoxifen
Strong CYP2D6 inhibitors among the SSRIs (paroxetine, fluoxetine) reduce conversion of tamoxifen to endoxifen, the principal active metabolite responsible for antiestrogen activity.
What you should do
Use citalopram, escitalopram, or venlafaxine in patients receiving tamoxifen; avoid paroxetine and fluoxetine.
Key facts
Severity
Major — avoid combination
Mechanism
Strong CYP2D6 inhibitors among the SSRIs (paroxetine, fluoxetine) reduce conversion of tamoxifen to endoxifen, the princ...
Action
Use citalopram, escitalopram, or venlafaxine in patients receiving tamoxifen; avoid paroxetine and fluoxetine.
Frequently asked questions
Can I take Ssri and Tamoxifen together?
No — this combination should generally be avoided. Use citalopram, escitalopram, or venlafaxine in patients receiving tamoxifen; avoid paroxetine and fluoxetine.
What is the severity of this interaction?
The interaction between Ssri and Tamoxifen is classified as Major — avoid combination. Strong CYP2D6 inhibitors among the SSRIs (paroxetine, fluoxetine) reduce conversion of tamoxifen to endoxifen, the principal active metabolite responsible for antiestrogen activity.
What should I do if I'm prescribed both?
Use citalopram, escitalopram, or venlafaxine in patients receiving tamoxifen; avoid paroxetine and fluoxetine. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.