All medications have the potential to cause side effects or adverse effects. Although the therapeutic effects of SSRI medication often take several weeks to manifest themselves, side effects (such as sleep difficulties or gastrointestinal symptoms) typically occur early and improve during the first several weeks of treatment. The majority of patients who take SSRI medication do not experience significant side effects. Nonetheless, some patients who take this medication for prolonged periods will experience adverse effects (such as weight gain, sleep disturbance, fatigue, or sexual dysfunction). When one medication in the SSRI class is ineffective or results in intolerable side effects, another SSRI medication may prove more effective or more tolerable.
The decision to use, or to continue to use, any medication rests on a risk-benefit analysis. If you and your physician are convinced that your medication is reducing or preventing your symptoms, and if you are experiencing no or few side effects, then it is likely that your physician will recommend your continuing this medication. This may be especially so in the case of OCD, where - as noted above - considerable distress or dysfunction may result from the untreated illness. That being said, you and your physician should periodically reevaluate this risk-benefit ratio.