What is Prozac?

Prozac (fluoxetine) is an antidepressant medication originally approved by the FDA in 1987 and currently available for the treatment of depression, obsessive-compulsive disorder, and bulimia nervosa. Prozac has also been used off-label (which means a use not reviewed by the FDA) to treat panic disorder. Prozac is believed to work by blocking the reabsorption of serotonin, a neurotransmitter or chemical messenger in the brain. It is a member of the serotonin-reuptake inhibitor (SSRI) family, as are Zoloft (sertraline) and Paxil (paroxetine).

How is Prozac different from other antidepressants?

Prozac is overall as effective in relieving depression as older tricyclic antidepressants (TCAs) such as imipramine. However, not all antidepressants are equally effective for a specific individual. Prozac causes fewer adverse heart-related events (such as a drop in blood pressure or unusual rhythm) and fewer anticholinergic effects (dry mouth, constipation, blurred vision, urinary retention) than TCAs. And it is less likely to cause drowsiness or weight changes also associated with the older TCAs. A special diet is not necessary when taking Prozac, which may be the case with other antidepressants known as monamine oxidase inhibitors (MAOIs). The incidences of death resulting from an overdose of Prozac have been extremely rare, which may help doctors feel more comfortable prescribing it.

What are the side effects of Prozac?

The most common side effects seen in people taking Prozac include anxiety or nervousness, insomnia, drowsiness, headache, diarrhea, and rash. In addition, sexual side effects (reduced arousal or satisfaction) may occur. Prozac has also been shown to cause changes in appetite and weight, usually resulting in weight loss rather than weight gain. Most side effects are mild and brief, usually subsiding in a week or two after beginning treatment. Particularly bothersome side effects can be treated with medication or by reducing the dose of the antidepressant, changing the time the medication is taken, or switching to a different antidepressant.

Is there a significant risk of suicide for people taking Prozac?

Suicide is always a risk in people with severe depression, and it may persist until significant remission occurs. However, consumers and their families must be cautious during the early stages of treatment with all antidepressants, when energy and activity may return before mood improves. At this time - when depression is still severe but when a depressed person may have more energy to take action - the risk of suicide can temporarily increase.

How does Prozac interact with other medications?

Prozac should not be taken until at least two weeks after MAOIs (e.g., Nardil and Parnate) are discontinued. Similarly, MAOIs should not be taken for at least five weeks after treatment with Prozac has been discontinued. The interaction between the two could produce fatal results. Consumers should always consult with their physicians when taking medications in addition to the prescribed antidepressant. Alcohol consumption should always be avoided when taking prescribed medications.

What is the standard dose of Prozac?

Prozac is used to treat depression, obsessive-compulsive disorder, and bulimia nervosa. For the treatment of depression and obsessive-compulsive disorder, a dose of 20 mg/day, taken in the morning, is recommended as the initial dose. A dose increase may be considered after several weeks if insufficient clinical improvement occurs. The maximum Prozac dose should not exceed 80 mg/day. For the treatment of bulimia nervosa, the recommended dose is 60 mg/day, taken in the morning. Prozac doses above 60 mg/day have not been systematically studied in people with bulimia.

How long should I take Prozac?

While there are no studies that answer the question of how long to continue Prozac, depression, obsessive-compulsive disorder, and bulimia nervosa are usually chronic conditions, and it is reasonable to consider longer term treatment for a consumer who is responding well. After 6 months, particularly for depression, it is reasonable to consider trying to reduce the dose to see whether symptoms return. As with other medications, discontinuing Prozac should be discussed with your doctor and a plan for discontinuation should be developed rather than simply stopping on your own. In clinical trials, Prozac's antidepressant efficacy has been maintained for periods of up to 38 weeks, following 12 weeks of acute treatment. For OCD and bulimia nervosa the efficacy of Prozac beyond 16 weeks has not been documented in controlled trials. However, people have continued in therapy for up to an additional six months without loss of benefit. Dose adjustments maintain the consumer on the lowest effective dosage, and consumers should be periodically reassessed to determine the need for continued treatment.

How soon after starting treatment will I feel better?

Someone starting treatment with Prozac may notice some improvement, particularly in concentration and increased energy, within one week. As with other antidepressants, it usually takes three to six weeks for the full therapeutic effect of the drug to be felt. The medication should be taken at the prescribed dose for six full weeks before evaluating its effectiveness.

Reviewed by Rex Cowdry, M.D., NAMI medical director, March 2001