I took Lisinopril for approximately 7 months. My main symptoms were that I could not think clearly (it has been very difficult to perform my job) and I was tired all of the time. When I finally decided to stop taking it, the fog lifted from my eyes and I had more energy. I like to have a drink once in a while and I had noticed that one of the side effects of Lisinopril was that I no longer had any tolerance for alcohol (I know I'm not supposed to drink). Drinking one beer gave me the same sensation as if I had four beers. One Friday (I was going on vacation) I decided to skip my dose so that I could go out and drink and have fun like I'm used to doing. The next morning the clarity of my thinking and my level of energy was dramatically increased. This is how I found out by accident (you could say irresponsibility) that Lisinopril was dragging me down. I have not touched Lisinopril since and I am working with my doctor on finding an alternative.