Key Takeaways

  • Prozac can cause side effects that range from mild to serious. Examples include nausea, insomnia, and sexual side effects, such as low sex drive and abnormal ejaculation.
  • Prozac’s side effects can change week by week, especially if your dosage is increased during your treatment.
  • Prozac has a boxed warning for the increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults.

Prozac is used in adults to help treat:

Prozac is used to help treat the following conditions in some children:

  • depression
  • depression related to bipolar I disorder when used with Zyprexa
  • OCD

Keep reading to learn about the common, mild, and serious side effects Prozac can cause.

Prozac has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). For details, see the “Side effects explained” section.

The following lists contain a few of the more common side effects reported by people who took Prozac in studies. These side effects can vary depending on the condition being treated.

Some common side effects in people taking Prozac for depression include:

Some common side effects in people taking Prozac for OCD include:

  • insomnia
  • nausea
  • diarrhea
  • decreased appetite and weight loss
  • sleepiness

Some common side effects in people taking Prozac for bulimia include:

Some common side effects in people taking Prozac for panic disorder include:

  • nausea
  • insomnia
  • diarrhea
  • nervousness
  • weakness or fatigue

To learn more about some of these side effects, see the “Side effects explained” section.

Mild side effects have been reported with Prozac. These include:

  • low sex drive
  • abnormal ejaculation
  • nausea
  • mild insomnia
  • unusual dreams
  • indigestion (upset stomach)
  • dry mouth
  • flu symptoms
  • skin rash
  • infection of the sinuses or throat
  • sweating
  • tremor (uncontrollable shaking in a part of your body)
  • nervousness
  • diarrhea
  • sleepiness
  • weakness or fatigue
  • mild anxiety

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Prozac unless your doctor recommends it.

Prozac may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

To learn more about some of these side effects, see the “Side effects explained” section.

Prozac may cause serious side effects. The following list may not include all possible serious side effects of the drug. For more information, you can refer to Prozac’s prescribing information.

If you develop serious side effects while taking Prozac, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported with Prozac include:

To learn more about some of these side effects, see the “Side effects explained” section.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking Prozac and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

Like most drugs, Prozac can cause an allergic reaction, including severe allergic reaction, in some people. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, usually in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an antihistamine you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Prozac, they’ll decide if you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Prozac, they may have you switch to a different treatment.

Children ages 10 to 17 years who take Prozac may experience the same side effects as adults.

Other side effects that may occur in children that weren’t reported in adults in studies include:

In addition, children have a higher risk of suicidal thoughts or behaviors than adults. This side effect is a boxed warning of Prozac. Boxed warnings are the most serious warnings from the FDA. To learn more, see the “Side effects explained” section.

Get answers to some frequently asked questions about Prozac’s side effects.

What side effects can Prozac cause week by week?

Prozac’s side effects may differ week by week, especially if your doctor increases your dosage during the course of treatment.

In the first week, side effects may include nausea, insomnia, anxiety, headache, fatigue, digestive issues, appetite changes, and sexual side effects. These effects are usually temporary and tend to ease as your system gets used to the drug, often within a few weeks.

Some serious side effects that you and your doctor will want to monitor when you first start Prozac treatment include agitation, thoughts of self-harm, or changes in mood, especially in children and younger adults. Suicidal thoughts are a boxed warning of Prozac. Boxed warnings are the most serious warnings from the FDA. To learn more, see the “Side effects explained” section.

Keep in mind that the side effects you experience may vary based on the condition you’re taking the drug to treat and the dosage your doctor prescribes. If you have questions about what to expect during treatment with Prozac, talk with your doctor.

Does Prozac cause different side effects in females versus males?

Prozac may cause different side effects in females than in males. Some people may have problems with their sex drive because of Prozac or their mental health condition. Females and males may experience this side effect differently.

Sexual issues in females taking Prozac may include a low sex drive and delayed or no orgasm. Males may have delays in ejaculation or lose the ability to ejaculate. Erectile dysfunction and low male sex drive are other effects males might have with Prozac.

People experiencing problems with their sex drive should talk with their doctor. Changes in sex drive are also symptoms of depression and other mental health disorders. Your doctor can help you manage problems with your sex drive while you’re taking Prozac.

Note: The use of binary terms such as “male” and “female” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

Do Prozac’s long-term side effects go away?

Long-term side effects of Prozac are uncommon. Most side effects of Prozac, such as headache, mild anxiety, and diarrhea, go away. Some long-term side effects that Prozac may cause include low sex drive, seizures, and an increased risk of bleeding.

Stopping Prozac can make long-term side effects go away. But do not stop taking Prozac without talking with your doctor first. Stopping this drug can make your condition worse.

Talk with your doctor about how to manage any side effects you may have from Prozac. If you need to stop taking Prozac because of long-term side effects, they may prescribe a different treatment for your condition.

Learn more about some of the side effects Prozac may cause.

Weight loss

Prozac can cause decreased appetite and weight loss. This side effect may be unwanted in people who are already underweight, especially since it’s possible to lose a significant amount of weight. Doctors are especially careful about monitoring the weight of children who take Prozac.

What might help

Weigh yourself regularly while you’re taking Prozac. A healthcare professional may also weigh you during your checkup appointments. Your child’s doctor will closely monitor the height and weight of your child while they take this drug.

If you’re concerned about weight loss with Prozac, talk with your doctor. They can help you reach and maintain a weight that’s healthy for you.

Anxiety

Anxiety is a common side effect of Prozac. It’s also a common side effect of other drugs in the same group of drugs as Prozac, called selective serotonin reuptake inhibitors (SSRIs).

With Prozac, anxiety can range from mild to severe and include symptoms such as:

What might help

When starting Prozac, you may feel temporarily anxious. This side effect may resolve on its own. But if your anxiety is severe, long lasting, or bothersome, talk with your doctor. They can suggest ways to reduce your feelings of anxiety.

If you’re feeling anxious, talk with your doctor before you stop taking Prozac. Stopping this drug can make your condition worse.

Risk of suicidal thoughts and behaviors

Prozac has a boxed warning for the risk of suicidal thoughts and behaviors. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

This side effect is most common in children, adolescents, and young adults under age 24 years. But it can happen to anyone taking Prozac or any antidepressant drug. Suicide is also a risk in people with depression who aren’t taking antidepressants.

Sometimes doctors prescribe Prozac for children under 18 years old. But due to these serious risks, they usually will not prescribe the drug for children ages 7 years or younger.

What might help

Report any changes in your mood or behavior to your doctor immediately. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Symptoms that may indicate an increased risk of suicide include:

If you have any of the above symptoms, your doctor may consider changing your medication. Do not stop taking Prozac without talking with them first. Stopping Prozac may make your condition worse.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Consider the following important information before starting Prozac.

Prozac has a boxed warning. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). For details, see the “Side effects explained” section.

Other precautions

Before taking Prozac, discuss your health history with your doctor. Prozac may not be right for you if you have certain medical conditions or other factors affecting your health. Your doctor can tell you what you should avoid while taking Prozac. Be sure to talk with your doctor if any of the following apply to you:

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses