How long does it take for Prozac to work?

When taking Prozac, it may take up to 4 to 6 weeks for your symptoms to fully improve. Some people may start to feel better in 1 to 2 weeks, while others may need 8 weeks or longer to feel the effects.

In a clinical research study, over half of the people who responded to treatment with Prozac had a positive benefit by the second week. Symptoms like anxiety, restlessness or fatigue may start to improve in the first 1 to 2 weeks. Your sleep, energy and appetite may improve over the first 4 weeks and you may have a better focus on daily tasks.

Continue to take your medication as directed by your healthcare provider. A depressed mood can take up to 8 weeks to fully respond. If you do not feel any relief at all from your symptoms after 2 to 4 weeks, you may need a dose adjustment or medication change. Contact your doctor, who can assess your response to treatment if you feel your treatment is not working.

Related: What does Prozac feel like when it starts working?

Prozac (generic name: fluoxetine) is in a group of antidepressants called selective serotonin reuptake inhibitors (SSRIs). It is thought to work by increasing levels of a chemical (neurotransmitter) in your brain called serotonin, although some studies have recently challenged this mechanism.

Prozac is approved by the FDA to treat:

• major depressive disorder
• obsessive compulsive disorder (OCD)
• panic disorder
• bulimia nervosa (an eating disorder)
• premenstrual dysphoric disorder (PMDD).

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How long do side effects last with Prozac?

Usually Prozac is started with a lower dose to help prevent any troublesome side effects, like severe stomach upset, anxiety, restlessness, insomnia (trouble sleeping), or nervousness. Over time, your doctor will slowly increase your dose and monitor your response.

In most people, these side effects will start to subside in a few weeks. In some cases, short courses of anti-anxiety or sleeping medicines may be prescribed until your medication takes full effect.

Prozac has a long half-life, which means it takes longer for the drug to reach effective levels and a “steady state” in your body. This also means it can take longer for the medicine, or any associated side effects, to leave your body if treatment is stopped. You should not stop taking Prozac treatment unless directed by your healthcare provider.

This is not all the information you need to know about Prozac (fluoxetine) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.