12 Prozac (Fluoxetine) Side Effects You Should Know About

If you have depression, you may be familiar with the antidepressant Prozac (fluoxetine). It's a popular selective serotonin reuptake inhibitor (SSRI) that has been around for decades. Beyond depression, Prozac is used for several other mental health conditions. These include obsessive-compulsive disorder (OCD), panic disorder, and bulimia.

If you're considering starting Prozac, you may feel hesitant due to its potential side effects. Although side effects are possible, they don't happen to everyone. And the good news is that for most people, many of them go away over time. But it's still important to know what to expect from treatment, and how to manage potential Prozac side effects.

Prozac (fluoxetine) side effects at a glance

Many Prozac side effects are mild and tend to improve over time. But in rare cases, more serious side effects are also possible.

Common Prozac side effects include:

• Nausea

• Insomnia

• Nervousness

• Anxiety

• Tremor (shakiness)

• Drowsiness

• Dry mouth

• Less appetite

• Diarrhea

• Weakness

• Sexual side effects, such as decreased libido (sex drive) and erectile dysfunction

• Cold and flu symptoms

• Sweating

Rare but serious Prozac side effects include:

• Serotonin syndrome

• Bleeding

• Angle-closure glaucoma

• Low blood sodium

• Abnormal heart rhythm

Prozac also has a boxed warning. This is the FDA's strictest warning for medications. Prozac's boxed warning is about an increased risk of suicidal thoughts and behaviors, particular in people under 25 years old.

Below, we cover 12 Prozac side effects and provide tips for how to manage them.

1. Insomnia

Like many SSRIs, Prozac can cause insomnia. That's because it raises the amount of serotonin in your brain. And serotonin is involved in many processes in the body, including mood regulation and sleep.

Compared to similar antidepressants, Prozac tends to be more energizing. So, you may have difficulty falling or staying asleep. Because of this, it's recommended to take it in the morning.

But if you're still having sleeping problems, let your prescriber know. They may decide to lower your dose, add another medication, or have you try another antidepressant. They can also provide tips for how to improve your sleep hygiene, such as optimizing your sleep environment.

2. Headache

Headache is a common side effect of SSRIs, including Prozac. For many people, headaches may improve as your body gets used to the medication. But if headaches become bothersome, talk to your healthcare team about over-the-counter options for relief. Acetaminophen (Tylenol) is one example. Keep in mind that nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin, Advil), can interact with Prozac. More on that later.

Headache can also be a symptom of low sodium levels in your body (called hyponatremia), which can happen with Prozac. This tends to be more common in older adults and people taking diuretics (water pills). Tell your prescriber if your headaches are accompanied by difficulty concentrating, confusion, or weakness.

3. Drowsiness

Although some people have trouble sleeping while taking Prozac, others may experience drowsiness. So, it's a good idea to see how the medication affects you before doing activities that require alertness, such as driving a car.

Drowsiness from Prozac may improve over time. But if it's interfering with your daily life, talk to your prescriber. While Prozac is usually taken in the morning, they may suggest trying to take it at night.

4. Anxiety and nervousness

In addition to insomnia, anxiety and nervousness are other activating side effects of Prozac. These side effects usually happen early in treatment and then improve with time. But for some people, they can be more intense and cause panic attacks.

It's important to tell your prescriber about any changes in your mood or behavior while taking Prozac. Although uncommon, these feelings may coincide with more serious issues, such as suicidal thoughts or behaviors (more on that later).

5. Nausea

Nausea is common with Prozac. It tends to happen within the first few weeks of treatment and should improve over time.

Prozac can be taken with or without food. But if you're feeling nauseous after your dose, try taking it with food to see if that helps. Tell your prescriber if your nausea doesn't go away or gets worse. They may decide to lower your dose or switch your antidepressant.

6. Sexual problems

Sexual problems are commonly reported with SSRIs, including Prozac. This can include a lowered sex drive, ejaculation or orgasm problems, and erectile dysfunction. Sexual side effects may improve over time for some people. But this isn't the case for everyone. It's also important to note that the cause of sexual problems can be complex.

Tell your prescriber if you notice any sexual problems while taking Prozac. In some cases, they may recommend adding or switching to a medication with fewer sexual side effects, such as bupropion.

7. Weight gain

Does prozac cause weight gain? Some people taking SSRIs such as Prozac may notice weight gain. This may be more likely if you smoke, don't exercise, or don't follow a healthy diet. Of the SSRIs, Prozac seems to cause the least amount of weight gain. And some people taking Prozac may lose weight.

Sometimes, weight gain may not be from the medication itself. As mentioned above, lifestyle factors may play a role. Plus, decreased appetite is a common symptom of depression and anxiety. As your symptoms improve, your appetite may improve as well. Healthy habits, including a balanced diet and regular exercise, can help you manage your body weight and provide mood-boosting benefits in the process.

But if you're concerned about weight gain while taking Prozac, talk to your prescriber for additional ways to minimize it. And if you've gained weight while taking Prozac, it's possible that you could lose weight after you stop taking it. Keep in mind that this can take time.

8. Sweating

Excess sweating is a common side effect of many antidepressants, including SSRIs like Prozac. If you find yourself sweating more than usual during treatment, wearing loose-fitting clothing and an antiperspirant may help.

But if sweating is still a problem, let your prescriber know. They may suggest lowering your dose or switching you to an antidepressant that's less likely to make you sweat. However, sweating can also be a symptom of serotonin syndrome, which we'll cover later.

9. Higher risk of bleeding

SSRIs, like Prozac, may raise your risk of bleeding, especially in your stomach. This is due to their effects on blood clotting cells (platelets). Tell your prescriber right away if you notice signs of bleeding, such as new or unusual bruising, blood in your stool, or black or tarry stool.

The risk of bleeding goes up if you're combining Prozac with other medications with a bleeding risk. Examples include NSAIDs and blood thinners like warfarin (Coumadin, Jantoven).

Make sure your prescriber and pharmacist have your current medication list. That way, they can review it for potential interactions. And it's best to double-check with them before adding a new medication or supplement to your regimen.

10. Antidepressant discontinuation syndrome

If you abruptly stop taking an antidepressant, or lower your dose too quickly, you may experience antidepressant discontinuation syndrome. Although temporary, this can cause unpleasant symptoms, such as flu-like symptoms, headache, and dizziness.

Compared to other antidepressants, Prozac sticks around in your body for a longer period of time. Because of this, it may have a lower risk of antidepressant discontinuation syndrome. Even so, it's still important to take Prozac as directed. Avoid discontinuing or lowering your dose on your own.

If you want to stop taking Prozac, talk to your prescriber first. They can help you do it safely to minimize or avoid these symptoms.

11. Serotonin syndrome

Serotonin syndrome is a condition that can happen when there's too much serotonin in your body. Although uncommon, it's possible with SSRIs since they raise serotonin levels.

Serotonin syndrome may be more likely if you combine Prozac with other medications that raise serotonin levels. Examples include other antidepressants, St. John's wort, and certain pain medications. Your prescriber or pharmacist can check for these potential interactions.

Signs of serotonin syndrome include sweating, shaking in your hands, and a fast heart beat. This can progress into confusion, high fever, and uncontrolled movements. In some cases, serotonin syndrome can be life-threatening. Contact your prescriber if symptoms develop. Seek medical care right away if your symptoms feel severe or life-threatening.

12. Suicidal thoughts and behaviors

If you take Prozac to help manage depression, your symptoms may get worse before they get better. Although uncommon, this can include suicidal thoughts and behaviors, especially in people under 25 years old.

Tell your prescriber right away if you notice changes in your mood or behavior. These changes may be more likely when starting treatment and after dosage adjustments.

If you or someone you know is having thoughts of suicide, 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.

Prozac (fluoxetine) side effects in women vs. men

Prozac can cause many of the same side effects in women and men, such as headaches and nausea. But when it comes to sexual side effects, men may experience lowered sex drive, ED, and ejaculation problems. Women may experience lowered sex drive and orgasm problems.

Menstrual cycle changes have also been reported in women taking Prozac. This includes heavy or prolonged menstrual bleeding. Talk to your prescriber if you notice that your periods are heavier than usual after starting Prozac.

When should you contact your healthcare team about Prozac side effects?

Many Prozac side effects tend to go away over time. But there are things you can do to help manage them as you're starting treatment. For example, changing when you take Prozac may help if you're experiencing insomnia or drowsiness.

But you don't have to wait for serious side effects to happen before talking to your healthcare team. If any Prozac side effects become bothersome or don't go away, they can help. They may decide to lower your dose, add another medication, or switch you to a different antidepressant. They can also give you more tips for how to improve your experience with the medication.

However, there are certain situations that warrant immediate medical attention. This can include serotonin syndrome and suicidal thoughts and behaviors.

Frequently asked questions