SSRIs are a second-line treatment of adult obsessive–compulsive disorder (OCD) with mild functional impairment and as first-line treatment for those with moderate or severe impairment. In children, SSRIs are considered as a second-line therapy in those with moderate-to-severe impairment, with close monitoring for psychiatric adverse effects.[31] SSRIs appear useful for OCD, at least in the short term.[32] Efficacy has been demonstrated both in short-term treatment trials of 6 to 24 weeks and in discontinuation trials of 28 to 52 weeks duration.[33][34][35] Clomipramine, a TCA drug, is considered effective and useful for OCD, however it is used as a second line treatment because it is less well tolerated than the SSRIs. Despite this, it has not shown superiority to fluvoxamine in trials.