In isolated cases the concurrent use of
SSRIs and
opioids (including fentanyl, hydromorphone, oxycodone, pentazocine, pethidine (meperidine), and possibly morphine) has resulted in the
serotonin syndrome. Methadone levels are modestly increased by
fluvoxamine,
paroxetine and sertraline, and possibly fluoxetine.
Serotonin syndrome, seems to be a rare occurrence, but the possibility should be borne in mind if an SSRI is given with one of these
opioids. Be aware that the use of
fluvoxamine,
paroxetine, sertraline or fluoxetine may alter the response to methadone. Monitor the outcome of concurrent use for methadone adverse effects.