Can ocd be cured? Get rid off from ocd?

Why Ocd (obsessive compulsive disorder) is tough to handle? My brother has been suffering from ocd since 2 to 3 yrs..He always thinking and doing reptitive actions again and again.He responds to social elements & he is a social activist too. Does hyper reactive and responding on environment and personal life situations triggers to OCD ? since 1 year he has been taking "Serotonin inhabitiors" tablets as per psychiatrist advise..His condition is better compared to previous than worse 1) why Ocd encounter to normal persons?why repetitive thoughts 2) but why sometimes reptitive thoughts coming in brain and triggers to do reptitive actions? Sometimes it is difficult to handle and feel embarrassing to see the OCD reptitive actions and condition.. Can we continuously taking Serotonin tablets for few more months...How to handle my brothers condition ? Does it cure permanently? How to get rid off from ocd? Please explain sir/Madam