Hello ! Thank you for your question, I’m Dr. Vikas (M.D Psychiatry) and I’ll try to help you today.
It is not necessary, usually for a first episode, patient is kept on medicine for a time period of 1 year in most cases.
if there is a history of 2 or 3 such episodes, then medicine can be prescribed for 3-5 year duration.
if there is a long history of illness with multiple remissions and exacerbation, in that case, treatment is continued for long term that is few years.
please feel free to discuss further if you have any other query.