Everybody feels sad or blue sometimes, whether as a result of a broken relationship, the death of a loved one, or financial difficulties. Some people aren't able to bounce back as easily as others and can become clinically depressed, says Dr, Donald Black, professor of psychiatry at the University of Iowa College of Medicine and staff physician at the UI Hospitals and Clinics. "This is a serious psychiatric condition that impairs people in all aspects of their lives. If severe enough and left untreated, it can kill," he says.

Noting that depression is an illness, not a weakness in character, Black says that many of these people can be treated with Fluoxetine (Prozac), which is an anti-depressant drug. Fluoxetine is believed to work by increasing the amount of serotonin in the brain. Serotonin is a neuro-transmitter--a chemical messenger--that helps transmit electrical impulses from one nerve ending to another. People suffering from clinical depression are believed to have lower than normal levels of serotonin.

Black is quick to note, however, that depression cannot be reduced to a mere chemical imbalance. "We don't want to forget that this illness deals with peoples lives, relationships, and emotions," he says.

How do you know if someone is clinically depressed? Symptoms include depressed mood, feeling sad or blue, loss of interest, lack of energy, loss of appetite, weight loss, poor or restless sleep, poor memory, inability to communicate, suicidal thoughts or behaviors, nervousness, restlessness, and loss of interest in sex.

People who experience such symptoms should see their physician, who may prescribe Fluoxetine, or some other type of anti-depressant as treatment. There are some potential side effects from using Fluoxetine, such as hyper-stimulation, agitation, and nervousness, but in most patients these disappear with time. "This is a safe, effective and well-tolerated drug with no significant side effects," Black says. "The only drawback is that it is expensive."