A medication taken to relieve symptoms of depression, which affects nearly half of those who have Parkinson’s. Paroxetine (Paxil) belongs to the class of drugs called selective serotonin REUPTAKE INHIBITOR (SSRI) MEDICATIONS. It extends the availability of serotonin, a neuro-transmitter important to brain functions related to mood and emotion. Paroxetine requires about four weeks to become fully effective. Paroxetine generally does not interact with anti-parkinson’s medications, although it, like other SSRIs, cannot be taken simultaneously with monoamine oxi-dase inhibitor (MAOI) or tricyclic antidepressant medications. Caution should be used when it is taken with selegiline, a selective monoamine oxi-dase-B inhibitor that some people with Parkinson’s disease take for its neuroprotective effects, as there is some theoretical risk of side effects from an excess of serotonin. Common side effects include headache and tremors, which often end at lower dosages or over time. sexual dysfunction is also common (typically decreased libido or delayed ejaculation) and may persist even with lower dose. Switching to a different drug within the SSRI classification often eliminates side effects.