I take 20 mg of Fluoxetine. I have vertigo and want to take 12.5 mg of meclizine. Is that okay?
There is considered to be a moderate interaction between Prozac (fluoxetine) and Antivert (meclizine). Meclizine can theoretically have its blood concentrations increased by fluoxetine, potentially increasing the risk of certain side effects such as:
Meclizine is classified as an antihistamine but is generally only used for motion sickness, nausea and vertigo. It is available in a variety of brand name products including Bonine and Dramimine Less Drowsy. The interaction with Prozac (fluoxetine) is due to changes in how the drug is metabolized and cleared from the body.
Prozac (fluoxetine) is a known inhibitor of the metabolizing enzyme CYP2D6. Meclizine is metabolized extensively by CYP2D6. Due to the inhibition of CYP2D6 by fluoxetine, meclizine may be metabolized less quickly, increasing blood concentrations higher than usual after dosing. This may enhance and intensify the effects of meclizine, potentially increasing the risk of adverse effects as discussed above.
There may be situations where the combination of both meclizine and fluoxetine are okay to be used. Generally, a lower than normal dose of meclizine (e.g. 6.25 to 12.5 milligrams) should be utilized in those taking fluoxetine until they know how they will react to the medication.