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What is A 22 years old woman presents with complaints of intense urge to shower. She spends hours showering and finds it difficult to get out of shower. She is also following same order of actions while bathing, scrubbing every body part 3 times in the same order. She is aware that this is abnormal but she becomes very anxious if she tries to break this pattern. She works as receptionist and is frequently late to her job because of this habit. She gets along well with friends at work. The drug of choice for treating her condition is: and explain in detail?
(Refer: Kaplan & Sadock's CTP  10th ed 16.4 P.4576)
Obsessive Compulsion disorder (OCD)

Defence mechanisms – Isolation of affect, Undoing, Reaction formation, Displacement, Repression & Denial
MC type of compulsion is Hand washing
Neurotransmitter – Decreased serotonin
DSM-IV Features of Obsession & compulsion