May 4, 2000 -- So you've skipped a couple of doses of your antidepressant ... so what? Or maybe you just decided to stop taking it ... what's the big deal? Researchers asking those very questions have found that suddenly stopping treatment with some antidepressants of the type known as selective serotonin reuptake inhibitors, or SSRIs, can cause serious withdrawal effects, both physically and psychologically.
SSRI drugs include those like Prozac, Paxil, and Zoloft. Patients taking these drugs must carefully follow their doctor's instructions about when and how long to take their medication. Failure to do so can lead to unpleasant problems, according to a study in the April issue of the British Journal of Psychiatry -- although some of the SSRI drugs seem to cause worse problems than others.
For those taking Paxil, especially, following the prescribed dosing instructions is important if you want to keep feeling well.
"Compliance with medication regimens as prescribed is important, and new symptoms can occur after missing doses," says the lead author of the study, David Michelson, MD. Michelson adds that in the case of the drug Paxil, negative symptoms can occur as early as the second missed dose.
"Symptoms related to discontinuation [and missed doses] commonly include physical symptoms such as dizziness and gastrointestinal symptoms," he says
Michelson and his colleagues studied 107 patients who had been successfully treated with Prozac, Zoloft, or Paxil. Over the course of 5 days, all of them received an inactive pill as a substitute for their medication, and this was compared with another 5-day period when all they took their regular medication. Patients reported side effects by filling out a questionnaire.
During the time they were taking the inactive tablet, patients treated with Paxil had more unpleasant -- and sometimes severe -- side effects than those who were treated with Zoloft. The most common symptom reported was dizziness. Unusual dreams, nausea, fatigue, and irritability were also common when after stopping Paxil and, to a lesser extent, Zoloft.
Researchers found that withdrawal from Prozac caused no negative events. They think this is due to the fact that Prozac stays in the body for a long time in comparison to the other SSRIs. If that is the case, withdrawal effects would not have been experienced after only 5 days of taking the inactive tablet.
The short period of the study -- especially given the long time Prozac stays active in the body -- can be thought of as a weakness in comparing the three drugs, says Raymond L. Woosley, PhD, who reviewed the study for WebMD. Complicating the issue, he says, is the fact that the company that paid for the study -- Eli Lilly and Company -- is the manufacturer of fluoxetine.
Woosley is professor and chairman of pharmacology at Georgetown University Medical Center in Washington, and a member of WebMD's editorial advisory board.
The bottom line, Michelson says, is that both doctors and patients need to pay more attention to the proper dosing schedules for antidepressants in the SSRI group. Adverse events can occur, but the good news is, they are most likely temporary. If patients experience any of these symptoms, and have not been taking their medicines regularly or as directed by their doctor, they should also know that the symptoms will probably resolve spontaneously once the medication is again taken regularly, he says.