MAJOR — Use With Caution
FDA-documented CYP2D6 interaction. Metoprolol levels can increase 4-6 fold. Consider beta-blockers not metabolized by CYP2D6 (atenolol, bisoprolol) or SSRIs with less CYP2D6 inhibition.
Evidence level: STRONG
Prozac (fluoxetine) can dramatically increase metoprolol levels in your blood by blocking the enzyme that breaks metoprolol down. This can cause your heart rate and blood pressure to drop dangerously low.
Fluoxetine is a potent CYP2D6 inhibitor. Metoprolol is extensively metabolized by CYP2D6. Fluoxetine can increase metoprolol levels 4-6 fold, causing excessive beta-blockade. FDA labels acknowledge CYP2D6 interactions.
If you take both medications, watch for signs of excessive beta-blockade (very slow heart rate, dizziness, fatigue). Your doctor may need to lower your metoprolol dose or switch to a different beta-blocker or antidepressant.
Take each at their prescribed times. Some SSRIs (fluoxetine, paroxetine) inhibit CYP2D6, which metabolizes metoprolol and propranolol — this can increase beta-blocker levels and cause more pronounced heart rate and blood pressure lowering. Monitor for dizziness or fatigue.
Higher risk for: elderly, those on multiple serotonergic drugs, people with liver impairment, CYP2D6 poor metabolizers, recent dose changes, or concurrent use of MAOIs or triptans.
Very slow heart rate (under 50 bpm), dizziness, lightheadedness, extreme fatigue, cold hands and feet, fainting, worsening of asthma symptoms
Consider switching to atenolol (not CYP2D6 dependent) or using sertraline/citalopram (weaker CYP2D6 inhibition). Monitor heart rate and blood pressure.
Discuss this combination with your prescriber. They may adjust timing, dosing, or switch to an alternative with fewer interaction risks. Never stop an antidepressant abruptly — taper under medical guidance.
Prozac (fluoxetine) can dramatically increase metoprolol levels in your blood by blocking the enzyme that breaks metoprolol down. This can cause your heart rate and blood pressure to drop dangerously low.
Take each at their prescribed times. Some SSRIs (fluoxetine, paroxetine) inhibit CYP2D6, which metabolizes metoprolol and propranolol — this can increase beta-blocker levels and cause more pronounced heart rate and blood pressure lowering. Monitor for dizziness or fatigue.
Very slow heart rate (under 50 bpm), dizziness, lightheadedness, extreme fatigue, cold hands and feet, fainting, worsening of asthma symptoms
Discuss this combination with your prescriber. They may adjust timing, dosing, or switch to an alternative with fewer interaction risks. Never stop an antidepressant abruptly — taper under medical guidance.
Consider switching to atenolol (not CYP2D6 dependent) or using sertraline/citalopram (weaker CYP2D6 inhibition). Monitor heart rate and blood pressure.
Or browse the full interaction database (121,000+ pairs).