Interaction Between Metoprolol & Paroxetine

In our latest question and answer, we discuss the potential interaction between metoprolol and paroxetine.

Nov 20, 2017

Kelle asked

I am on paroxetine 40 mg and metoprolol 25 mg for fast heartbeat. Are they safe to take together? I take one in the morning. And one at night. 


There is a documented interaction between paroxetine and metoprolol, although the effects are generally mild.

Metoprolol may have its concentrations in the body increased when taken with paroxetine. This is due to paroxetine altering a major metabolizing enzyme, CYP2DP.

Paroxetine is known to inhibit the metabolizing enzyme CYP2D6. This may lessen the ability of the enzyme to metabolize others drugs that are a substrate for it, such as metoprolol, resulting in higher concentrations than normal. While this typically isn't considered a major interaction as the effects are generally minimal, it is good to be aware of and know that dose adjustments of metoprolol may be needed.

Separating the administration of both drugs most likely won't help in avoiding the interaction. This is due to paroxetine staying in the body for long periods of time when taken consistently and therefore, has a constant effect on CYP2D6.

If you are having side effects, such as hypotension, dizziness or sedation, let you doctor know so they can evaluate your medication regimen.

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