Side Effects of Prozac: What You Need to Know

Prozac (fluoxetine) is a prescription drug used to treat certain mental health conditions, including depression. Prozac can cause side effects that range from mild to serious. Examples include weight loss, abnormal dreams, and abnormal ejaculation.

Prozac is used in adults to help treat:

major depressive disorder (depression)
depression related to bipolar I disorder*
treatment-resistant depression*
obsessive-compulsive disorder (OCD)
panic disorder with or without agoraphobia
bulimia nervosa (an eating disorder)

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

depression
depression related to bipolar I disorder*
OCD

* Prozac is used in combination with another drug called Zyprexa (olanzapine) for this condition.

Prozac comes as a capsule that you swallow. It contains the active ingredient fluoxetine. (An active ingredient is what makes a drug work.)

Prozac can cause many mild to serious side effects. This drug also has many warnings to consider. Keep reading to learn about the common, mild, and serious side effects that Prozac can cause.

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For a general overview of the drug, including details about its uses, see this article.

Below are a few of the more common side effects reported by people who took Prozac in studies. Side effects can vary depending on the condition the drug is being used to treat. But note that side effects don’t happen to everyone.

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

nausea
insomnia (trouble sleeping)
nervousness
diarrhea
anxiety*

Some common side effects in people taking Prozac for obsessive-compulsive disorder (OCD) include:

insomnia
nausea
diarrhea
decreased appetite and weight loss*
sleepiness

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

insomnia
nausea
weakness or fatigue (low energy)
sleepiness
anxiety*

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

nausea
insomnia
diarrhea
nervousness
weakness or fatigue

Continue reading to learn about other mild and serious side effects of Prozac.

* To learn more about this side effect, see the “Side effects explained” section below.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Prozac, visit MedWatch.

Mild side effects have been reported with Prozac. Below are just some of the mild side effects seen in the drug’s studies.

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

* To learn more about this side effect, see the “Side effects explained” section below.

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.

Prozac can cause serious side effects. These sometimes occur in people with mental health conditions such as a history of bipolar disorder or suicidal thoughts or behaviors.

Serious side effects that have been reported with Prozac include:

seizure
serotonin syndrome (a high level of the chemical serotonin)
mania (very high energy and excited behavior)
bleeding
hyponatremia (low sodium levels in the blood)
insomnia (trouble sleeping)
severe anxiety*
decreased appetite and weight loss*
severe allergic reaction*
risk of suicidal thoughts or behaviors†

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.

* To learn more about this side effect, see the “Side effects explained” section below.
† Prozac has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section below.

Help is out there

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

Call the 988 Suicide and Crisis Lifeline at 988.
Text HOME to the Crisis Textline at 741741.
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.

Does Prozac cause different side effects in women versus men?

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.

Men may have delays in ejaculation or lose the ability to ejaculate. Erectile dysfunction and low sex drive are other effects men might have with Prozac. Sex drive issues in women taking Prozac may include low sex drive and delayed or no orgasm.

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. Doctors can help you manage problems with your sex drive while you’re taking Prozac.

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Can Prozac cause long-term side effects?

Long-term side effects of Prozac are uncommon. Most side effects of Prozac, such as headache, mild anxiety, and diarrhea, don’t last long. Some long-term side effects that Prozac may cause include seizure, low sex drive, and 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.

How do low dose Prozac side effects compare with those seen with higher doses?

When taking low dose Prozac, some side effects may occur less often. Certain side effects of Prozac are more common with a higher dose.

For example, doctors usually prescribe higher doses of Prozac for people with bulimia compared with other conditions. So some side effects in people taking Prozac for bulimia occur more often than they do in people taking the drug for other conditions. These include anxiety and trouble sleeping.

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

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 age 18 years. 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:

anxiety
panic attacks
trouble sleeping
irritability or agitation
mania (very high energy and excited behavior)

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.

Weight loss

Prozac can cause decreased appetite and weight loss. This side effect can 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. Doctors will closely monitor the height and weight of children taking 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:

restlessness
trouble concentrating
irritability
tiredness

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.

Allergic reaction

Like most drugs, Prozac can cause an 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.

what dose of the drug you were taking when you had the side effect
how soon you had the side effect after starting that dose
what your symptoms were
how your symptoms affected your daily activities
what other medications you were taking
any other information you feel is important

Prozac can cause many mild to serious side effects. It also has several warnings to consider.

Boxed warning: 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). It alerts doctors and patients about effects of the drug that may be dangerous.

Worsening depression and risk of suicidal thoughts and behaviors can happen to anyone taking Prozac. But the risk of these side effects is greater in people under age 24 years. If your doctor prescribes this drug for you, they’ll monitor you closely for signs and symptoms of these risks.

To learn more, see the “Side effects explained” section above.

Other warnings

Prozac may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether Prozac is a good treatment option for you. Talk with your doctor about your health history before starting this drug. Factors to consider include those described below.

Liver problems. Tell your doctor if you have liver problems, such as cirrhosis. Prozac is broken down in your liver. If you have liver problems, the drug may not break down properly and can build up in your system. This can increase your risk of side effects. Your doctor may prescribe a lower dose or a less frequent dose of Prozac for you.

Heart condition. Prozac can cause or worsen arrhythmias (irregular heart rhythm conditions) such as torsades de pointes. Tell your doctor if you have a personal or family history of problems with your heart rhythm. They may still prescribe Prozac for you but will regularly check your heart function using an electrocardiogram (ECG).

Alcohol and Prozac

Alcohol may interfere with Prozac. Before taking Prozac, ask your doctor how much, if any, is safe for you to drink with this drug.

Pregnancy and breastfeeding while taking Prozac

Tell your doctor if you’re pregnant or plan to become pregnant while taking Prozac. Taking Prozac late in your pregnancy can increase your baby’s risk of needing:

a long stay in the hospital
breathing support
feeding by a tube

It can also increase their risk of pulmonary hypertension (high blood pressure within the lungs).

If you are or become pregnant while taking Prozac, consider enrolling in the drug’s pregnancy registry. Reporting the effects of Prozac during pregnancy helps researchers better understand the drug’s risks to mother and child. To register, call the National Pregnancy Registry for Psychiatric Medications at 844-405-6158 or visit the website.

Prozac passes into breast milk. Children exposed to this drug through breast milk may experience:

agitation
irritability
poor feeding
poor weight gain

Tell your doctor if you’re breastfeeding or planning to breastfeed while taking Prozac. They’ll weigh the benefits of breastfeeding with the possible risks to your baby.

Mild side effects from Prozac are common but usually go away with time. Serious side effects of Prozac are rare, but some can be life threatening. To determine whether Prozac might be right for you, tell your doctor about your medical and family history.

If you have questions about side effects that Prozac can cause, talk with your doctor. Examples of questions to help get you started include:

Which antidepressants usually cause fewer suicidal thoughts and behaviors than Prozac?
If I lose weight while taking Prozac, should I lower my dose since I now weigh less?
Can I drive while taking Prozac?
If I have trouble sleeping while taking Prozac, which sleeping pills can I safely take?
Can taking Prozac with a high fat meal help improve my sleep?

To learn more about Prozac, see these articles:

Prozac side effects: What you should know
Dosage Details for Prozac

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Disclaimer: Austra Health 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

Last medically reviewed on March 20, 2023