Evidence antidepressants don't make you high: They have no street value.(GETTY IMAGES)

Antidepressant medications such as Prozac and Zoloft are so popular they're advertised on television. But the same drug that gives your co-worker relief might make you jittery or cause weight gain. Watch as this patient describes her efforts to find the right medication for her depression.

Antidepressants work—though exactly how, why, and for whom is a complicated question.

More about antidepressants

Some 65% to 85% of people who take them improve within six to nine months. One study tracking more than 100 patients who took antidepressants and participated in talk therapy found that this combination prevented 80% of the subjects from relapsing.

Symptom relief can take weeks
How antidepressants work is a subject of ongoing research and speculation. The prevailing theory is that they boost chemicals in the brain, especially the neurotransmitters serotonin and neuropinephrine, that make you feel better.

But scientists at Johns Hopkins University recently suggested an alternative theory: that antidepressants make brain cells regenerate.

You may start to feel better within one to three weeks of taking antidepressant medicine. But it can take as many as six to eight weeks to see further improvement. If you have questions or concerns about your medication or if you don't notice any improvement by the three-week mark, talk to your doctor.

"A misconception about antidepressant medications is that they affect everyone the same way," says Tracey Lipsig Kite, a psychologist in private practice in Evanston, Ill. "Some people are so sensitive to the side effects, and there are others who are fine with the side effects but for whom the meds don't work at all."

[ pagebreak ]Don't expect a "high"
Antidepressants aren't like narcotics or alcohol. They don't make you high, or cause hangovers. Their effectiveness is gradual and the benefits are subtle.

"People who respond to antidepressants find that their sadness is more subject to logic—they can talk themselves out of it," says George I. Papakostas, MD, an assistant professor of psychiatry at Harvard Medical School. "You tend to feel less nervous, and you're better able to control worries. Energy levels go up, and you take pleasure again in your hobbies, friends, and loved ones."

The drugs may also help relieve physical manifestations of your depression—like neck pain or backaches, he says.

"It's not like a Disney movie, where you wake up and the birds are chirping," says Kate Meyers, 47, who lives near Boulder, Colo. She has had success with Zoloft and Effexor XR. "The drugs don't make you happy, they make you even."

She says that people tease her about her "happy pills," but she describes them differently: "I feel calm and relief on the drugs. Bad news and difficulties don't incapacitate me when I'm on medication."

What about side effects?
Roughly 20% to 30% of people experience side effects serious enough to make them stop taking the medication. Minor side effects such as headache, nausea, diarrhea, dizziness, sweating, tremor, and dry mouth usually ease or go away within a few days or weeks.

More serious or annoying side effects include nervousness and agitation, panic, insomnia, daytime drowsiness, loss of libido or other sexual problems, and weight gain. In very rare cases patients may experience an increase in suicidal thoughts.

Sometimes such side effects can be serious enough that you should ask your doctor to adjust or switch your medication.

"I ask my patients to come in for a visit within one to two weeks after I prescribe an antidepressant, to make adjustments, if necessary," says Dr. Papakostas. Sometimes lowering the dosage can eliminate side effects.

Psychiatrists usually recommend avoiding alcohol if you are depressed and/or taking an antidepressant because alcohol is itself a depressant.

And since most of the drugs are equally effective, if you dislike the side effects of the one you're taking, you can usually switch. "I took Lexapro, but I got so jumpy that I stopped taking it," says Meyers.

Zoloft provided her with the calm and relief she was looking for: "I felt like I was coming to peace with myself, and I was better able to use humor to diffuse bad feelings."

Later, when she felt a need to go back on the drugs, she tried Effexor XR, which worked just as well. "There doesn't seem to be any rhyme or reason to it," she says. "When they work, the drugs function so that you're not fighting yourself."