Good explanation of how SSRIs work on depression, what makes them different from other antidepressants, and side effects of SSRI antidepressants.

Prime Candidates for Treatment of Depression

The SSRIs are particularly helpful in heading off depression in the early stages, before it becomes deeply rooted. Some studies suggest that SSRIs are ideal for those people with minor depressive illness -- much better than tricyclics, such as imipramine, or the complication-prone MAOIs. The SSRIs are effective for major depression, too.

Research seems to suggest that you can head off serious full-blown illness by taking an SSRI during the early stages of depression.

This doesn't mean that SSRIs are the only worthwhile antidepressant, of course. There is still a place for the older drugs. Research has shown that the older tablets (Tricyclics) are just as effective as the newer ones (SSRIs) but, on the whole, the newer ones seem to have fewer side-effects. A major advantage of the SSRIs is that they are not so dangerous if someone takes an overdose.

Researchers also note that the SSRIs don't work for 20 percent to 40 percent of depressed or anxious people who try them -- the same failure rate as for the older antidepressants.

Which SSRI Is Best?

Most experts agree that no single SSRI is better than the rest. Each antidepressant drug has a certain profile of its own particular side effects; some have markedly similar side effects, while others vary widely.

For example, Zoloft and Paxil don't last as long in the body as Prozac; the half-life of Zoloft is about 26 hours, and the half-life of Paxil is about 21 hours. ("Half-life" is the time it takes for a drug in the blood to decrease by half of its original dose.)

It's important to understand that all the SSRIs may cause nausea, headache, anxiety, dry mouth, insomnia, and a variety of sexual dysfunctions. But as mentioned, what makes Prozac less desirable is that it lingers in the body much longer than other SSRIs; up to six weeks after you stop taking the drug, traces of Prozac and its metabolites can still be found in your body. If you have a bad reaction to Zoloft or Paxil, symptoms last for a week or two. But side effects while taking Prozac can last for up to six weeks before all traces of the drug leave your body.

Of course, none of the SSRIs are any sort of wonder drug. They all have some side effects, although they are less severe than those of other antidepressants.

One of the biggest problems with some of these drugs is their cost. The branded versions are much more expensive than the generic versions of older drugs like some of the SSRIs, MAOIs or tricyclics. Generic versions of the older drugs are available because their patents have expired.

No matter how wonderful a drug may be, if you can't afford it, it's not going to do you much good. The high cost of the SSRIs can be a real hardship for someone with no insurance, or whose insurance doesn't cover drugs. At about $2 to $3 per pill, the pharmacy bill can be overwhelming.

It's a problem for Mary, 28, whose health insurance covers all drugs except medications for mental health problems. "My psychiatrist is very aware of this problem," Mary explains. "He doesn't give me Zoloft alone because it would be too expensive. So he prescribes a smaller amount of Zoloft with desipramine (a less-expensive tricyclic)." The desipramine boosts the effects of Zoloft, and the combination costs less than a full dose of Zoloft alone.

SSRI Antidepressants, Suicidal Feelings and Young People

There is evidence of increased suicidal thoughts and behaviors and other side effects in young people taking antidepressants. So SSRI antidepressants, with the exception of Prozac, are not approved by the FDA for use in people under 18.

In fact, in 2004, the FDA ordered the strongest safety warning possible:

Antidepressants increase the risk of suicidal thinking and behavior (suicidality) in children, adolescents and young adults (up to age 24) with major depressive disorder (MDD) and other psychiatric disorders. Anyone considering the use of [Drug Name] or any other antidepressant in a child or adolescent must balance this risk with the clinical need.

There is no clear evidence of an increased risk of self-harm and suicidal thoughts in adults over 24. But, individuals mature at different rates. Young adults are more likely to commit suicide than older adults, so a child, teen or young adult should be particularly closely monitored if he or she takes an SSRI antidepressant.