Intrusive thought
Antidepressants which have been shown to be effective in treating OCD include fluvoxamine (trade name Luvox), fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), citalopram (Celexa), and clomipramine (Anafranil). Although SSRIs are known to be effective for OCD in general, there have been fewer studies on their effectiveness for intrusive thoughts. A retrospective chart review of patients with sexual symptoms treated with SSRIs showed the greatest improvement was in those with intrusive sexual obsessions typical of OCD. A study of ten patients with religious or blasphemous obsessions found that most patients responded to treatment with fluoxetine or clomipramine. Women with postpartum depression often have anxiety as well, and may need lower starting doses of SSRIs; they may not respond fully to the medication, and may benefit from adding cognitive behavioral or response prevention therapy.
Anxiety disorder
Obsessive–compulsive disorder (OCD) is not classified as an anxiety disorder by the DSM-5 but is by the ICD-10. It was previously classified as an anxiety disorder in the DSM-IV. It is a condition where the person has obsessions (distressing, persistent, and intrusive thoughts or images) and compulsions (urges to repeatedly perform specific acts or rituals), that are not caused by drugs or physical order, and which cause distress or social dysfunction. The compulsive rituals are personal rules followed to relieve the anxiety. OCD affects roughly 1-2% of adults (somewhat more women than men), and under 3% of children and adolescents.