Obsessive-compulsive disorder (OCD) is a mental illness that, if not treated early, can badly affect the people living with it, an expert says.

Psychiatrist specialist of Pantai Hospital in Sungai Petani Dr Mohammad Farris Iman Leong Abdullah said OCD could affect the daily life of the person to the extent of not being able of working or having friends, or worst, experiencing symptoms of psychotic disorder, such as hallucination.