How Long Does It Take for Prozac to Work? (Plus, 4 More Prozac FAQs)
Key takeaways:
How long it takes for Prozac (fluoxetine) to work can vary. For depression, Prozac can start to improve symptoms within 2 weeks. But it may take 4 to 8 weeks to reach its full effect.
When Prozac starts working, you should feel an improvement in your symptoms. For depression this may include feeling less down, tired, and anxious. And the medication’s side effects often lessen or go away over time.
Prozac is available as a lower-cost generic. GoodRx may be able to help you save over 80% off the average retail price of generic Prozac at certain pharmacies.
Table of contents
Prozac (fluoxetine) is an antidepressant medication. More specifically, it's a selective serotonin reuptake inhibitor (SSRI). Prozac is FDA approved to treat depression in adults and children who are at least 8 years old. And beyond depression, it’s approved to treat conditions such as panic disorder, bulimia nervosa, and obsessive-compulsive disorder (OCD) in people at least 7 years old.
If you have a prescription for Prozac, you’ll want to learn a few facts about this medication. For example, you may be wondering how long Prozac takes to work, and what it feels like when Prozac starts working. Here, we’ll answer five frequently asked questions to help you get the most out of your Prozac prescription.
1. How long does it take for Prozac to work?
How long Prozac takes to work depends on what is being treated. And the amount of time it takes to see improvement in symptoms can vary from person to person.
Depression
According to the American Psychiatric Association (APA), it can take somewhere between 4 to 8 weeks for antidepressants to reach their full effect. But it’s possible for some symptoms to improve after just 2 weeks of treatment with Prozac. If 4 weeks have passed without any improvement in your depression symptoms, talk to your healthcare provider. They may increase your dose or recommend trying another medication.
OCD
It may take 4 to 6 weeks to see a noticeable improvement in OCD symptoms. And for some people, it may take up to 12 weeks to see any improvement. If 4 weeks have passed and you don’t feel any improvement, your healthcare provider might increase your dose. But don’t make any changes to your dose without talking to your provider first.
Bulimia
We don't know exactly how long it takes Prozac to reduce bulimia symptoms. But studies have found that people who respond well to Prozac as a treatment for bulimia typically do so by 3 weeks of treatment. Talk to your healthcare provider if you don’t notice any improvement in your bulimia symptoms after taking Prozac for a few weeks. They may recommend switching to another medication.
Panic disorder
After starting treatment with Prozac, some panic disorder symptoms may improve within 3 to 4 weeks. But for many people, it can take up to 4 to 6 weeks to start feeling better. If 6 weeks have passed and you don’t see any improvement in your symptoms, your healthcare provider may recommend increasing your dose or switching to another medication.
2. What does Prozac feel like when it starts working?
Now that we’ve discussed how long Prozac takes to work for most people, you may be wondering how you’ll feel when the medication starts working. The most important thing to look for is improvement in your symptoms.
Below are some examples of symptoms that can improve with Prozac, based on the condition being treated:
Depression: You may notice that you feel less down and less tired a few weeks after starting treatment with Prozac. You may have fewer mood swings and less anxiety or worry.
OCD: You may experience less obsessions (intense anxiety-inducing thoughts) and compulsions (repetitive behaviors) with the medication.
Panic disorder: Prozac may help you experience less panic attacks, anticipatory anxiety, and avoidance.
Bulimia: Prozac can help reduce your desire to binge eat or throw up.
Talk to your healthcare provider if you’re concerned that Prozac isn’t working for you. They can help you decide what to do next. This may include increasing your dose or switching to another antidepressant.
3. Does it matter what time of day you take Prozac?
It’s best to take Prozac in the morning. This is because it’s known to cause sleep issues.
Prozac is one of the more “activating” antidepressants. So it may not be the best option for you if you already have trouble sleeping. Talk to your healthcare provider about any sleep issues you have before taking an antidepressant. They can help you choose one that’s less likely to worsen your sleep if needed.
4. Should I take Prozac with food?
Prozac can be taken with or without food.
Research shows that Prozac is one of the least likely SSRIs to cause nausea. But it’s still a possible side effect. In clinical studies, more than 20% of people taking Prozac experienced nausea.
If Prozac is making you nauseated, try taking it with food. If that doesn’t help, talk to your healthcare provider about trying another SSRI. Each person is different, and you may have less nausea with another antidepressant.
5. Will I experience side effects from Prozac?
Prozac can cause several side effects. But this doesn't mean you'll experience any or all of them. Still, it’s important to be aware of the common side effects, including:
Trouble sleeping
Headache
Sexual problems
Nervousness and anxiety
Dry mouth
Nausea
Diarrhea
Prozac can also cause more serious side effects. While rare, it’s good to be aware of the potential for:
Serotonin syndrome: This is a medical condition caused by too much serotonin in the body. Serotonin syndrome is more likely to occur if Prozac is combined with other medications that raise serotonin levels, such as tramadol, sumatriptan (Imitrex), and lithium.
Abnormal heart rhythms: This is more likely to occur in people with existing heart problems and those who take other medications that can affect heart rhythms.
Higher risk of bleeding: This is more likely if you take other medications that cause bleeding, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or anticoagulants.
Greater risk of suicidal thoughts or behavior: This increased risk for suicidal thoughts and behavior specifically is more likely in people who are 24 years old and younger.
Manic episodes: Prozac can lead to manic episodes, or periods of high energy, in people with bipolar disorder.
When should I contact my healthcare provider about Prozac side effects?
Most of Prozac’s common side effects go away within a few weeks of treatment. But if you’ve been taking Prozac for some time and you’re still experiencing side effects, talk to your healthcare provider. They may recommend ways to manage them. Or if your side effects are persistent and bothersome, they may be able to adjust your dose or prescribe a different antidepressant.
If you’re experiencing any serious side effects — like a fast heartbeat, bleeding or bruising, or an unusual rash — contact your healthcare provider immediately. And if you or someone you know is having thoughts of suicide, know that you’re not alone and help is available. Call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.
How can you save on Prozac?
There are many ways to save on Prozac, which is available as both a brand-name and generic medication:
Save with GoodRx. GoodRx may be able to help you save over 80% off the average retail price of fluoxetine, the generic version of Prozac. Fluoxetine capsules may be as low as $ with a free GoodRx coupon. And fluoxetine tablets may be as low as $.
Save with patient assistance programs. If you’re uninsured or have Medicare Part D, you may be eligible for Prozac’s patient assistance program, which may offer the medication free of cost.
The bottom line
Prozac (fluoxetine) is a selective serotonin reuptake inhibitor (SSRI) that’s FDA approved to treat a variety of mental health conditions, including depression. How long it takes for Prozac to work can vary. It can start to have antidepressant effects within 2 weeks of treatment. But it may take up to 4 to 8 weeks to reach its full effect.
When Prozac starts working, you should feel an improvement in your symptoms. If you’re taking Prozac for depression, you may find that you have more energy, experience less mood swings, and feel happier overall.
Common side effects of Prozac include nausea, trouble sleeping, and headaches. These side effects usually go away as your body adjusts to the medication. Serious side effects are rare, but they can occur. These include a greater risk of bleeding, abnormal heart rhythms, and suicidal thoughts. Talk to your healthcare provider about the risks and benefits of Prozac before starting treatment.
Why trust our experts?
References
American Psychological Association. (n.d.). Anticipatory anxiety. American Psychological Association Dictionary of Psychology.
American Psychological Association. (n.d.). Avoidance. American Psychological Association Dictionary of Psychology.
Gelenburg, A. J., et al. (2010). Practice guidelines for the treatment of patients with major depressive disorder – Third edition. American Psychiatric Association.
Institute for Quality and Efficiency in Health Care. (2023). Depression: How effective are antidepressants? InformedHealth.org.
Lambert, M. (2008). APA releases guidelines on treating obsessive-compulsive disorder. American Family Physician.
Stein, M. B., et al. (2010). Practice guideline for the treatment of patients with panic disorder - Second edition. American Psychiatric Association.
Sysko, R., et al. (2009). Early response to antidepressant treatment in bulimia nervosa. Psychological Medicine.
Tollefson, G. D., et al. (1994). How long to onset of antidepressant action: A meta-analysis of patients treated with fluoxetine or placebo. International Clinical Psychopharmacology.
Wang, Z., et al. (2022). Risks of digestive system side-effects of selective serotonin reuptake inhibitors in patients with depression: A network meta-analysis. Therapeutics and Clinical Risk Management.
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