Paroxetine is part of a class of drugs called selective serotonin reuptake inhibitors, or SSRIs for short. SSRIs act on a specific chemical in the brain known as serotonin. Serotonin is one of several chemicals used to send messages from one nerve cell to another.
As a message travels down a nerve, it causes the end of the cell to release serotonin. The serotonin enters the gap between the first nerve cell and the one next to it. When enough serotonin reaches the second nerve cell, it activates receptors on the cell and the message continues on its way. The first cell then quickly absorbs any serotonin that remains in the gap between cells. This is called "reuptake."
Normally, this process works without any problems. But when the levels of serotonin become unbalanced, it can cause a variety of conditions, including depression. Paroxetine helps to block the reuptake of serotonin so more serotonin remains in the space between the brain's nerve cells. This gives the serotonin a better chance of activating the receptors on the next nerve cell.
There have been several studies that looked at the effects of using paroxetine to treat various conditions.
Studies have shown paroxetine to be effective for depression treatment in adults. People taking it had more improvement in their depression symptoms, compared to those not taking it. Also, long-term studies have shown that it can help prevent relapse (when depression comes back).
In studies, up to 24 percent of adults with obsessive-compulsive disorder (OCD) who took paroxetine felt their OCD was "much improved," compared to only 11 percent of those who were not taking it. Only 3 to 7 percent of people taking it felt that their OCD was worse, compared to 14 percent of people not on paroxetine.