Paroxetine and Tamoxifen: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Paroxetine and Tamoxifen unless specifically directed by your doctor.
How Paroxetine interacts with Tamoxifen
Paroxetine is a potent CYP2D6 inhibitor and blocks the conversion of tamoxifen to its active metabolite endoxifen, reducing antitumour efficacy and increasing breast cancer recurrence risk.
What you should do
Use a non-CYP2D6-inhibiting antidepressant such as venlafaxine, escitalopram, or mirtazapine when concurrent therapy is required.
Key facts
Severity
Major — avoid combination
Mechanism
Paroxetine is a potent CYP2D6 inhibitor and blocks the conversion of tamoxifen to its active metabolite endoxifen, reduc...
Action
Use a non-CYP2D6-inhibiting antidepressant such as venlafaxine, escitalopram, or mirtazapine when concurrent therapy is ...
Frequently asked questions
Can I take Paroxetine and Tamoxifen together?
No — this combination should generally be avoided. Use a non-CYP2D6-inhibiting antidepressant such as venlafaxine, escitalopram, or mirtazapine when concurrent therapy is required.
What is the severity of this interaction?
The interaction between Paroxetine and Tamoxifen is classified as Major — avoid combination. Paroxetine is a potent CYP2D6 inhibitor and blocks the conversion of tamoxifen to its active metabolite endoxifen, reducing antitumour efficacy and increasing breast cancer recurrence risk.
What should I do if I'm prescribed both?
Use a non-CYP2D6-inhibiting antidepressant such as venlafaxine, escitalopram, or mirtazapine when concurrent therapy is required. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.