How long after discontinuing fluvoxamine can one start taking duloxetine?

Generally, it is safer to wait at least 5 days after discontinuing fluvoxamine before starting duloxetine. However, if a monoamine oxidase inhibitor (MAOI) has been used previously, this interval should be extended. If any abnormal symptoms occur, prompt medical consultation is recommended. Detailed analysis is as follows:

Fluvoxamine is a selective serotonin reuptake inhibitor (SSRI), while duloxetine is a serotonin-norepinephrine reuptake inhibitor (SNRI). Both drugs improve mood by modulating neurotransmitters. If MAOIs have not been co-administered, it is generally advised to wait at least 5 days after stopping fluvoxamine before initiating duloxetine, allowing sufficient time for the drug to be metabolized and eliminated from the body. This helps prevent potential additive effects between residual fluvoxamine and the newly introduced duloxetine.

If the patient has previously taken an MAOI antidepressant concurrently, strict adherence to the guideline—"discontinue MAOI for at least 14 days before starting another antidepressant"—is essential. Combining MAOIs with either fluvoxamine or duloxetine may lead to serotonin syndrome, a potentially life-threatening condition characterized by symptoms such as high fever, muscle rigidity, and altered mental status. Therefore, when MAOIs have been used, the washout period must be significantly prolonged.

During the transition period, patients should closely monitor for any adverse effects such as dizziness, nausea, or anxiety. If these symptoms persist or worsen, immediate contact with a healthcare provider is necessary to adjust the treatment plan. Patients should never alter their medication dosage without medical supervision.