Fluoxetine Oral Capsule: Side Effects, How to Take, and More (2024)

What is fluoxetine oral capsule?

If you have certain mental health conditions, your doctor may prescribe fluoxetine for you.

It’s a prescription medication that’s used in certain situations to treat:

• major depressive disorder, which is also called depression
• obsessive-compulsive disorder
• moderate or severe bulimia nervosa
• panic disorder

Depending on its prescribed use, fluoxetine capsules can be used in adults and some children.

For more information about these conditions and how fluoxetine is used for them, see the “What is fluoxetine oral capsule used for?” section below.

Fluoxetine oral capsule basics

You’ll take fluoxetine oral capsules by mouth.

They belong to a group of medications called selective serotonin reuptake inhibitors (SSRIs).

Note: Fluoxetine also comes in other forms that you’ll take by mouth. These forms include delayed-release capsules, liquid solution, and tablets. (Delayed-release capsules release their active drug over a certain length of time. This is unlike immediate-release capsules, which release their active drug soon after you take them.) Only immediate-release oral capsules are described in this article. If you’d like to learn about fluoxetine’s other forms, talk with your doctor or pharmacist.

Fluoxetine oral capsule brand-name versions

Fluoxetine is a generic drug. The brand-name version of fluoxetine oral capsules is called Prozac.

Note: The other forms of fluoxetine have other brand-name drug versions. To learn about those other versions, talk with your doctor or pharmacist.

Fluoxetine oral capsules are a generic drug, which means they’re an exact copy of the active drug in a brand-name medication. The brand-name medication that fluoxetine oral capsules are based on is called Prozac.

Generic drugs are thought to be as safe and effective as the brand-name drug they’re based on. In general, generics usually cost less than brand-name drugs do.

If you’d like to know more about using Prozac instead of fluoxetine oral capsules, talk with your doctor. Read this Healthline article to learn more about the differences between generic and brand-name drugs.

What are fluoxetine oral capsule’s side effects?

Like most drugs, fluoxetine oral capsules may cause mild or serious side effects. The lists below describe some of the more common side effects that fluoxetine oral capsules may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

• your age
• other health conditions you have
• other medications you may be taking

Your doctor or pharmacist can tell you more about the potential side effects of fluoxetine. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that fluoxetine oral capsules can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read fluoxetine oral capsule’s prescribing information.

Mild side effects of fluoxetine oral capsules that have been reported include:

• diarrhea
• dry mouth
• feeling anxious
• fatigue (having less energy than usual)
• hot flashes
• indigestion
• loss of appetite
• nausea or vomiting
• sexual side effects*
• sweating more than usual
• swelling or irritation in your throat and nasal cavity
• tremors
• unusual dreams
• weakness

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information on this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from fluoxetine oral capsules can occur, but they aren’t common. If you have serious side effects from fluoxetine oral capsules, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of fluoxetine oral capsules that have been reported include:

• trouble sleeping
• abnormal or heavy bleeding
• low sodium level
• serotonin syndrome (a condition in which you have a buildup of the brain chemical serotonin in your body)
• long QT syndrome (a certain heart condition)
• boxed warning: risk of suicidal thoughts and behaviors in certain people*
• weight loss*
• allergic reaction*

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects fluoxetine oral capsules may cause.

Boxed warning

Fluoxetine oral capsules have boxed warnings. A boxed warning is a serious warning from the Food and Drug Administration (FDA).

Risk of suicidal thoughts and behaviors in certain people. Like other drugs used to treat depression, fluoxetine may increase the risk of suicidal thoughts and behaviors. Specifically, the drug may increase this risk in people ages 24 years and younger.

This side effect is more likely to occur when you first start taking the medication and any time your doctor adjusts your dosage.

It’s important to note that having depression or another mental health condition is itself a risk factor for suicidal thoughts and behaviors. And fluoxetine is used for some of these conditions.

In studies, antidepressant use didn’t increase the risk of suicidal thoughts and behaviors in people older than age 24 years. And in people ages 65 years and older, these drugs actually decreased this risk.

What might help

If you notice changes in your thoughts or behaviors while you’re taking fluoxetine, call your doctor right away. If you have thoughts of suicide or attempt to harm yourself, get medical attention immediately. You may need to call 911 or your local emergency number.

Your doctor may talk with your family, such as a partner or parent, while you’re taking fluoxetine. They may ask your family to help monitor you for any changes in your thinking or behaviors while you’re taking this drug.

Suicide Prevention

If you think someone is at immediate risk of self-harm or hurting another person:

• Call 911 or your local emergency number.
• Stay with the person until help arrives.
• Remove any guns, knives, medications, or other things that may cause harm.
• Listen, but don’t judge, argue, threaten, or yell.

If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Weight loss

It’s possible to have weight changes while you’re taking fluoxetine. For example, weight loss was reported by people taking the drug in studies. But it was rarely a reason for them to stop taking the drug.

Some people taking fluoxetine may be at higher risk for this side effect. This includes people with depression who are considered underweight, as well as people with bulimia nervosa.

What might help

Talk with your doctor if you’re concerned about weight changes while you’re taking fluoxetine. They can suggest ways to help you maintain a weight that’s healthy for you.

Sexual side effects

You may have sexual side effects with fluoxetine.

Sexual side effects have been reported with other selective serotonin reuptake inhibitors (SSRIs), too. (Keep in mind that fluoxetine belongs to the group of drugs called SSRIs.)

Sexual side effects reported by people taking fluoxetine in studies include:

• impotence (problems with having or keeping an erection)
• decreased libido (sex drive)
• abnormal ejacul*tion

It’s important to note that mental health conditions can also cause changes in sexual desire and performance. This includes depression, which fluoxetine is used to treat.

What might help

Talk with your doctor if you have sexual side effects while you’re taking fluoxetine. They may recommend treatment for this side effect. In some cases, they may recommend that you stop taking fluoxetine and try a different medication.

Allergic reaction

Some people may have an allergic reaction to fluoxetine oral capsules.

Symptoms of a mild allergic reaction can include:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to fluoxetine oral capsules. But if you think you’re having a medical emergency, call 911 or your local emergency number.

How is fluoxetine oral capsule taken?

Your doctor will explain how you should take fluoxetine. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Taking fluoxetine oral capsule

You’ll take fluoxetine oral capsules by mouth. They come in these strengths:

• 10 milligrams (mg)
• 20 mg
• 40 mg

Dosage

The dosage of fluoxetine your doctor prescribes will depend on the reason you’re taking the drug. It’s used to manage:

• major depressive disorder (MDD), which is also called depression
• obsessive-compulsive disorder (OCD)
• moderate or severe bulimia nervosa
• panic disorder

For MDD, OCD, and bulimia nervosa, it’s recommended you take fluoxetine in the morning. For panic disorder, there’s not a best time of day recommended to take the drug.

Doses of 40 mg and 80 mg are on the high end of fluoxetine’s dosage range. The maximum recommended dose of fluoxetine is 80 mg.

Taking fluoxetine oral capsule with other drugs

Fluoxetine oral capsules may be taken alone, or they may be used together with other drugs.

Additionally, fluoxetine comes in a combination pill with the drug olanzapine. This combination drug is a brand-name medication called Symbyax.

Symbyax is used to treat bipolar I disorder, as well as treatment-resistant depression. (This form of depression doesn’t improve with certain treatments.) Fluoxetine oral capsules shouldn’t be used by themselves to treat these conditions.

Questions about taking fluoxetine oral capsule

Here’s a list of common questions related to taking fluoxetine oral capsules.

• What if I miss a dose of fluoxetine oral capsules? If you miss a dose of fluoxetine, take it as soon as you remember. But if it’s close to the time to take your next dose, simply skip the missed dose. Then, take your next dose as scheduled. You shouldn’t take an extra dose to try and make up for a missed dose. Doing so can increase your risk for side effects.
• Will I need to use fluoxetine oral capsules long term? This depends on decision-making between you and your doctor. It also depends on the condition you’re taking fluoxetine to treat. You may take fluoxetine either short term or long term.
• Can fluoxetine oral capsules be chewed, crushed, or split? No, you shouldn’t chew, crush, or split fluoxetine capsules. They’re meant to be swallowed whole. Talk with your doctor or pharmacist if you have trouble swallowing these capsules.
• Should I take fluoxetine oral capsules with food? Fluoxetine capsules may be taken with or without food.
• How long do fluoxetine oral capsules take to work? Like other medications used to treat depression, fluoxetine doesn’t start working right away. It can take 2 to 6 weeks before you notice a reduction in your symptoms. Talk with your doctor or pharmacist if you have more questions about when you’ll see improvement with fluoxetine treatment.

Questions for your doctor

You may have questions about fluoxetine oral capsules and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

• Before your appointment, write down questions such as:
  • How will fluoxetine oral capsules affect my body, mood, or lifestyle?
• Bring someone with you to your appointment if doing so will help you feel more comfortable.
• If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

What should be considered before taking fluoxetine oral capsule?

Some important things to discuss with your doctor when considering treatment with fluoxetine include:

• your overall health
• any medical conditions you may have
• any medications you’re taking

These considerations and others are described in more detail below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking fluoxetine oral capsules, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with fluoxetine oral capsules.

Interactions with drugs or supplements

Fluoxetine oral capsules can interact with several types of drugs. These drugs include:

• other drugs used to treat depression, such as:
  • other selective serotonin reuptake inhibitors
  • serotonin-norepinephrine reuptake inhibitors
  • monoamine oxidase inhibitors
  • tricyclic antidepressants
• nonsteroidal anti-inflammatory drugs, including aspirin
• the blood thinner warfarin
• the anxiety drug buspirone
• the attention deficit hyperactivity disorder drug Adderall
• the Tourette syndrome drug pimozide
• the schizophrenia drug thioridazine
• the seizure medications phenytoin (Dilantin) and carbamazepine (Tegretol)
• the mental health drug lithium (Lithobid)
• certain medications for treating abnormal heart rhythms, including:
  • amiodarone (Pacerone)
  • sotalol (Betapace)

This list does not contain all types of drugs that may interact with fluoxetine oral capsules. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of fluoxetine oral capsules.

Boxed warning

Fluoxetine oral capsules have a boxed warning about an increased risk of suicidal thoughts and behaviors in certain people. A boxed warning is a serious warning from the Food and Drug Administration (FDA).

For more information about this warning, see the “What are fluoxetine oral capsule’s side effects?” section above.

Other warnings

Fluoxetine oral capsules may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take fluoxetine oral capsules. Factors to consider include those in the list below.

• Bipolar disorder. You may be at higher risk for having mania or hypomania if you have bipolar disorder and take fluoxetine. Your doctor will likely screen you for bipolar depression before they prescribe fluoxetine for you. If you already know you have this condition, be sure your doctor is aware of this before you take fluoxetine. Fluoxetine isn’t approved to treat bipolar depression.
• Seizures. It’s possible that fluoxetine could increase the risk of seizures in people who already have them. Before you take fluoxetine, talk with your doctor if you have seizures or have had them in the past.
• Angle-closure glaucoma. Fluoxetine can cause your pupils to dilate (widen). This can cause angle-closure glaucoma in some people. You may be at higher risk for this condition if you have certain eye conditions. Talk with your doctor about whether you should have your eyes examined before you start taking fluoxetine.
• Low sodium level. Certain drugs used for depression, including fluoxetine, can cause your level of sodium to be low. You may be at higher risk for this if you take a diuretic or you’re older than 65 years of age. If you already have a low blood sodium level, the condition may worsen with fluoxetine. Your doctor can help determine whether fluoxetine is safe for you to take.
• Heartbeat problems. Taking fluoxetine can lengthen a part of your heartbeat pattern called the QT interval. If you already have long QT syndrome, taking fluoxetine could worsen your condition. Your doctor may monitor you more closely while you take fluoxetine. Or they may recommend that you take a different medication.
• Driving and operating machinery. Like other drugs used for treating depression, fluoxetine could cause problems with your judgment, thoughts, and motor skills. This could impact your ability to perform certain tasks, such as driving or operating machinery. Ask your doctor what activities you should avoid until you know how fluoxetine affects you.
• Liver problems. Your liver metabolizes (breaks down) and gets rid of fluoxetine after you take a dose. If you have liver problems, you may need a lower dosage of fluoxetine to avoid having too high levels of the drug in your body. Having a high level of the drug can increase your risk for side effects from the drug. Talk with your doctor and make sure they’re aware of any liver problems you have before you take fluoxetine.
• Allergic reaction. If you’ve had an allergic reaction to fluoxetine oral capsules or any of their ingredients, you shouldn’t take the capsules. Ask your doctor what other medications are better options for you.

Use with alcohol

You shouldn’t drink alcohol while you’re taking fluoxetine.

Alcohol and fluoxetine can cause some of the same side effects, such as:

• feeling anxious
• having less energy than usual
• nausea or vomiting
• sexual side effects
• sweating more than usual
• tremors

Additionally, both alcohol and fluoxetine can cause problems with your judgment, thoughts, and motor skills.

Keep in mind that drinking alcohol can also worsen liver disease. If you have liver disease, such as cirrhosis (liver scarring), how well your body clears fluoxetine may be reduced. This can increase the level of fluoxetine in your body, raising your risk for side effects.

Before you take fluoxetine, talk with your doctor if you drink alcohol. They can suggest ways to help you avoid alcohol. Or they may prescribe a different medication for your condition.

Pregnancy and breastfeeding

Here’s some information about taking fluoxetine oral capsules while you’re pregnant or breastfeeding.

Use in pregnancy

Studies have shown that when antidepressant drugs such as fluoxetine are used in the third trimester, they can increase the risk of complications at birth.

But other studies have shown that people with depression who stop taking their antidepressant during pregnancy are more likely to have their depression symptoms worsen. This is in comparison with people who kept taking their antidepressant.

If you’re pregnant or planning on becoming pregnant, talk with your doctor before taking fluoxetine. They can discuss with you the risks and benefits of using this drug.

Use while breastfeeding

Fluoxetine is known to pass into breast milk. There are reports of side effects in breastfed children exposed to the drug. These side effects include agitation and trouble feeding.

Talk with your doctor about the risks and benefits of breastfeeding while taking fluoxetine. They can discuss the safety of breastfeeding versus using other options to feed your child.

What are some frequently asked questions about fluoxetine oral capsule?

Find answers to some commonly asked questions about fluoxetine oral capsules.

Is fluoxetine used to treat COVID-19 or anxiety?

No, fluoxetine isn’t used for COVID-19. And its use for anxiety depends on the type of anxiety that’s occurring.

Some ongoing studies are looking to see if fluoxetine can help prevent COVID-19 from becoming serious. The drug isn’t currently approved for this use. For up-to-date information on COVID-19, including approved treatments and vaccine information, check out this page.

Fluoxetine is only approved to treat symptoms of a panic attack in people who have panic disorder. According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), panic disorder is a type of anxiety disorder. (The DSM-5 is used to diagnose mental health conditions. For more information about it, see this article.)

Fluoxetine may be used off-label to treat other anxiety disorders. (With off-label use, a drug is prescribed for a condition it isn’t approved to treat.)

If you’re interested in learning more about off-label uses of fluoxetine, ask your doctor or pharmacist.

Can stopping fluoxetine lead to withdrawal symptoms?

Yes, you may have withdrawal symptoms when you’re stopping fluoxetine treatment. These symptoms can include:

• feeling irritable or agitated
• dizziness
• anxiety
• confusion
• headache
• problems falling asleep

There have been rare reports of these symptoms being serious in some people.

You’re more likely to have withdrawal symptoms from stopping fluoxetine if you suddenly quit taking the drug. For this reason, you shouldn’t stop taking fluoxetine without talking with your doctor or pharmacist. They can suggest ways to slowly decrease your dose over time.

How does fluoxetine work? What’s its half-life?

For treating depression, fluoxetine’s mechanism of action (how it works) is to increase levels of serotonin in your brain and body.

It’s thought that depression and some other mental health conditions are caused by certain brain chemicals being out of balance. Examples of these chemicals include serotonin and dopamine.

It’s not known exactly how the drug works for its other uses. But fluoxetine likely works by balancing certain brain chemicals.

Fluoxetine’s half-life is about 4 to 6 days. (A drug’s half-life is the time it takes for your body to get rid of half of a dose of the drug.)

Is fluoxetine similar to fluvoxamine?

Fluoxetine and fluvoxamine (Luvox) are similar, but they do have some differences.

Both fluoxetine and fluvoxamine belong to a group of drugs called selective serotonin reuptake inhibitors (SSRIs). SSRIs are used to treat mental health conditions, such as depression.

Fluvoxamine is only used to treat obsessive-compulsive disorder (OCD). This is unlike fluoxetine, which is used to treat OCD, plus some other mental health conditions, including depression.

If you have more questions about how fluoxetine and fluvoxamine are alike and different, talk with your doctor or pharmacist.

Is fluoxetine used for weight loss? If so, what’s the dosage for weight loss?

Fluoxetine isn’t approved for weight loss. But this is a possible side effect of the drug.

Fluoxetine may be used off-label for weight loss. (With off-label use, a drug is prescribed for a condition it isn’t approved to treat.) But because this isn’t an approved use of the drug, there’s not a recommended dosage for it.

If you’re interested in learning more about off-label uses of fluoxetine, ask your doctor or pharmacist.

Does fluoxetine cause weight gain?

Weight gain wasn’t reported in people taking fluoxetine during studies.

Keep in mind that loss of appetite can be a symptom of depression, which fluoxetine is used to treat. Some people find that using an antidepressant, such as fluoxetine, causes this symptom to go away, and their appetite returns to normal. This could lead to weight gain.

If you’re concerned about weight gain while you’re taking this drug, talk with your doctor. They can recommend ways to help you manage a weight that’s healthy for you.

What is fluoxetine oral capsule used for?

If you have certain mental health conditions, your doctor may prescribe fluoxetine for you.

It’s a prescription medication that’s used in certain situations to treat:

• Major depressive disorder (MDD). For this condition, the drug is given to adults and children ages 8 years and older. MDD is also called depression. With this condition, you have long-lasting feelings of sadness and a loss of interest. It consists of episodes of symptoms that last for at least 2 weeks, but the episodes often last longer.
• Obsessive-compulsive disorder (OCD). For this condition, the drug is given to adults and children ages 7 years and older. With OCD, you have obsessions that lead to compulsive behaviors. For example, you may have obsessive worries about your house being unlocked, leading you to feel compelled to constantly check whether the door is locked.
• Moderate or severe bulimia nervosa. For this condition, the drug is given to adults. Bulimia nervosa is sometimes just called bulimia. It’s an eating disorder that consists of episodes of binge eating followed by purging.
• Panic disorder. For this condition, the drug is given to adults. With panic disorder, you have panic attacks, and you may have anxiety about having a panic attack.

It’s thought that depression and some other mental health conditions are caused by certain brain chemicals being out of balance. Examples of these chemicals include serotonin and dopamine. Fluoxetine works by helping to increase or balance levels of certain brain chemicals.

Fluoxetine may also be prescribed off-label to treat other mental health conditions, such as anxiety. With off-label use, a drug is prescribed for a condition it isn’t approved to treat. If you’re interested in learning more about off-label uses of fluoxetine, ask your doctor or pharmacist.

What should be done in case of overdose?

Don’t take more fluoxetine oral capsules than your doctor prescribes. Using more than this can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

• fast heart rate
• nausea
• seizures
• drowsiness

What to do in case you take too much fluoxetine oral capsule

Call your doctor if you think you’ve taken too many fluoxetine oral capsules. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

What should I know about fluoxetine oral capsule vs. sertraline?

Fluoxetine (Prozac) and sertraline (Zoloft) are similar, but they also have some differences.

Fluoxetine and sertraline both belong to a group of drugs called selective serotonin reuptake inhibitors (SSRIs). SSRIs are used to treat mental health conditions such as depression and obsessive-compulsive disorder.

Sertraline is also approved to treat some additional conditions including social anxiety disorder and post-traumatic stress disorder. Unlike fluoxetine, sertraline isn’t approved to treat bulimia.

To learn more about the differences and similarities between Prozac and Zoloft, see this comparison. Also, check with your doctor about which drug is better for you.

What does fluoxetine oral capsule cost?

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

Financial assistance to help you pay for fluoxetine oral capsules may be available. Medicine Assistance Tool and NeedyMeds are two websites that provide resources to help reduce the cost of fluoxetine oral capsules.

These websites also offer tools to help you find low-cost healthcare and certain educational resources. To learn more, visit their websites.

What to ask your doctor

Talk with your doctor if you have questions about using fluoxetine. It’s a prescription drug that’s used in certain people to treat:

• major depressive disorder, which is also called depression
• obsessive-compulsive disorder
• moderate or severe bulimia nervosa
• panic disorder

You may want to ask your doctor about other treatments for these conditions. Below are a few articles you may find helpful:

• How Can I Get Help for Depression?
• What Medications Help Treat Depression?
• What Are the Treatment Options for OCD?
• Is Therapy an Effective Treatment for Eating Disorders?
• Panic Disorder with Agoraphobia

Here are a few questions you may want to ask your doctor about fluoxetine:

• How will I know if fluoxetine is working to treat my condition?
• Should I use other treatments for my condition while I’m taking fluoxetine?
• Can I take fluoxetine with acetaminophen (Tylenol)?

Ask a pharmacist

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 other 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.