The treatment for depression does not necessarily have to be long. Most of the people show positive response within three months.  The time taken for the treatment to work will largely depend on the type of treatment you have opted for and also how deep is your depression. Initially the doctor will analyze your behavior and various other things in order to determine what type of depression you are going through. Once this is determined, they will suggest you treatment that suits best for you and have better chances to work on you effectively. All this process may sound complex but most of the patience start recovering within months.   

There are several treatments that take time to come into effect. These treatments are mostly meant for the people who are suffering from major depression and also have many other health problems. So, extra care has to be taken in order to deal with such patients. Long term treatment will prevent a person from getting recurring depression and most of them work quite effectively. Thus, the treatment may take long time or short time depending on various factors. Lastly, if the person himself wants to get rid of the depression then the treatment will work really fast on them.