I was told by several health professionals that it can be for some who have bipolar illness - especially if your illness has a regular pattern of high, lows, & normal times. I have only taken Lithium, and it has helped, however, I have not taken it long enough to know if it will be the only thing I will need to take. Some people have taken it for years and have been successful with it, while others have had to find something new due to side effects or it no longer working. The person who plays "Sonny", on General Hospital I think only takes this and has done so for 14 years with good success. Usually it is one of a few mood stabilizers that is tried first to see if it works and then additional drugs are added or replace it.