Fanapt (iloperidone) is a prescription tablet used to treat schizophrenia in adults. Fanapt can cause side effects that range from mild to serious. Examples include dizziness and sleepiness.

Keep reading to learn about the common, mild, and serious side effects Fanapt can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild to serious side effects during Fanapt treatment. Examples of the drug’s more commonly reported side effects include:

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

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

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

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Fanapt, but this side effect wasn’t reported in studies. However, these reactions have happened since Fanapt was approved for use.

Serious side effects have been reported with Fanapt. These include:

If you develop serious side effects while taking Fanapt, 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.
† In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.
‡ An allergic reaction is possible after taking Fanapt, but this side effect wasn’t reported in studies. However, these reactions have happened since Fanapt was approved for use.

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

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

How do side effects of Fanapt compare with those of Risperdal?

Fanapt and Risperdal (risperidone) are both antipsychotic drugs used to treat schizophrenia. (Risperdal is also approved to treat other conditions as well.)

Fanapt and Risperdal can cause similar side effects, such as:

  • movement problems
  • restlessness
  • weight gain
  • orthostatic hypotension
  • long QT syndrome*

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

In studies, some of these side effects were reported more often with one drug than the other. For example, long QT syndrome and orthostatic hypotension occurred more often with Fanapt. But movement problems and restlessness were more common with Risperdal.

Keep in mind that your risk of side effects with either drug depends on many different factors. These include the dosage you’re prescribed, your health history, and other medications you take.

To learn more about how Fanapt compares with Risperdal, talk with your doctor. They can help determine whether one of these drugs is a better option for you.

Does Fanapt cause long-term side effects?

It’s possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away, even after you stop taking the drug.

Examples of long-term side effects reported in Fanapt’s studies include:

  • metabolic changes, such as weight gain, high blood sugar, high cholesterol, and high triglyceride levels
  • tardive dyskinesia (unusual body movements that you can’t manage)

Talk with your doctor to learn more about possible side effects of Fanapt and how long they may last.

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

Increased risk of death in certain older adults

Fanapt has a boxed warning for the increased risk of death in certain older adults. A boxed warning is the most serious warning from the FDA. It alerts doctors and patients about drug effects that may be dangerous.

Antipsychotic drugs, such as Fanapt, increase the risk of death in older adults with psychosis related to dementia.

Psychosis (loss of touch with reality) is a symptom of schizophrenia, which Fanapt is used to treat. Psychosis can also occur with dementia. Fanapt is not approved to treat dementia-related psychosis.

What might help

Due to the risk, doctors typically will not prescribe Fanapt to treat psychosis related to dementia in older adults. For more information about this warning or other treatment options for dementia-related psychosis, talk with your doctor.

Long QT syndrome

Fanapt can cause long QT syndrome, which is a type of irregular heart rhythm. This side effect wasn’t commonly reported in studies of Fanapt.

Long QT syndrome can cause serious, even life threatening irregular heartbeat. It may cause symptoms such as:

  • feeling like your heart is racing, pounding, or skipping beats
  • dizziness
  • lightheadedness
  • fainting

Factors that can raise the risk of long QT syndrome when taking this drug include:

What might help

Before starting Fanapt, be sure to talk with your doctor about your health history and tell them about any other medications you take. They’ll usually avoid prescribing Fanapt with other drugs that can cause long QT syndrome. And if you have a heart condition, they may order an electrocardiogram (EKG) to check your heart before prescribing this drug for you.

While taking Fanapt, check with your doctor or pharmacist before taking any new medications to make sure the combination is safe for you.

If you have symptoms of an irregular heartbeat during treatment with Fanapt, talk with your doctor right away. They’ll likely have your heart rhythm checked with an EKG. If it’s confirmed you’ve had a change in your heart rhythm with Fanapt, they may have you switch to a different treatment.

Allergic reaction

Like most drugs, Fanapt can cause an allergic reaction in some people. This side effect wasn’t reported in studies but has been reported since the drug came on the market. 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 oral antihistamine, 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 Fanapt, they’ll decide whether 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 Fanapt, they may have you switch to a different treatment.

Keeping track of side effects

During your Fanapt treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • 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

Keeping notes and sharing them with your doctor will help them learn more about how Fanapt affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Fanapt.

Boxed warning: Increased risk of death in certain older adults

Fanapt has a boxed warning for the increased risk of death in certain older adults. A boxed warning is the most serious warning from the FDA.

Fanapt can increase the risk of death in older adults with psychosis related to dementia. To learn more, see the “Side effects explained” section above.

Other warnings

Fanapt can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Fanapt is a good treatment option for you. Talk with your doctor about your health history before starting this drug. Be sure to tell them if any of the following factors apply to you:

  • heart problems, such as irregular heart rhythm, slow heart rate, heart failure, long QT syndrome, or recent heart attack
  • low levels of potassium or magnesium in your blood
  • prone to dehydration
  • low blood pressure
  • diabetes
  • liver problems
  • high blood pressure
  • high cholesterol or triglycerides
  • seizure disorders, such as epilepsy
  • low white blood cell count or a history of this with other drugs
  • difficulty swallowing
  • prone to heat exposure (such as working or exercising outdoors in a hot climate)
  • previous allergic reaction to Fanapt
  • pregnancy
  • breastfeeding

Alcohol and Fanapt

You should avoid drinking alcohol during treatment with Fanapt. Alcohol can raise your risk of side effects from the drug, such as sleepiness and dizziness or lightheadedness, especially upon standing up.

Drinking alcohol can also worsen some of the symptoms of schizophrenia, which Fanapt is used to treat.

If you have questions about consuming alcohol during Fanapt treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Fanapt

There’s limited information about the safety of taking Fanapt during pregnancy or while breastfeeding.

Pregnancy

It’s not known whether it’s safe to take Fanapt during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor before starting treatment with this medication.

If you take this drug while pregnant, consider signing up for the National Pregnancy Registry for Atypical Antipsychotics by visiting the website or calling 866-961-2388. A pregnancy registry collects information about the safety of certain drugs when used during pregnancy.

Breastfeeding

It isn’t known whether Fanapt is safe to take while breastfeeding. Your doctor will likely recommend that you don’t breastfeed while taking this medication. If you’re currently breastfeeding or planning to do so, talk with your doctor about the best way to feed your child while taking Fanapt.

Like most drugs, Fanapt can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects Fanapt can cause, talk with your doctor. Examples of questions to help get you started include:

  • Does my risk of Fanapt side effects depend on my dosage?
  • How often do serious side effects occur with Fanapt?
  • Will I need any monitoring for side effects while taking this medication?

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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.