Fenfluramine for Treating Epilepsy

New research suggests that this obesity drug may reduce seizures

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Fintepla (fenfluramine) is a prescription medication approved for the prevention of seizures associated with Dravet syndrome and Lennox Gastaut syndrome in adults and children age 2 and older. It comes as an oral solution, and the dosing is weight-based. This medication is often taken with other anti-epilepsy drugs (AEDs), and the dose may be adjusted if it's taken with other AEDs.

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Fenfluramine is considered a very effective appetite suppressant, and, in the past, it was approved by the FDA for the treatment of obesity.

Fenfluramine was an ingredient in the popular product Fen-Phen, and it was also marketed under the name Pondimin. Fenfluramine was found to cause serious side effects, including heart valve thickening and pulmonary hypertension. It was taken off the market worldwide in the late 1990s due to these safety concerns.

The manufacturer of Fintepla provides information regarding the monitoring of side effects.


This medication is approved for long-term daily use for preventing seizures associated with Dravet syndrome and Lennox-Gastaut syndrome.

Fenfluramine is an amphetamine derivative, which means that it is closely related to the epinephrine and norepinephrine that your body makes naturally. These stimulants speed up the heart rate, increase blood pressure, decrease appetite, and slow down digestion. The chemical similarity to amphetamine is believed to be the mechanism by which fenfluramine suppresses appetite, and it is also responsible for some of the side effects.

Fenfluramine also increases serotonin (5 HT), a neurotransmitter that primarily works in the brain, gastrointestinal system, and platelets.

Dravet Syndrome

Children and adults with Dravet syndrome usually experience several types of refractory seizures (i.e., those that cannot be controlled with standard medical management), including tonic-clonic seizures and myoclonic seizures. These happen frequently—often multiple times a day.

Often, several AED treatments are used to prevent the seizures associated with Dravet syndrome, and many people who have the condition need to have adjustments in the medication regimen throughout the years.

Off-Label Uses

Fintelpa has been prescribed off-label for treating refractory seizures in conditions such as:

  • Sunflower syndrome, a rare condition in which people who have photosensitive epilepsy expose themselves to flashing lights to self-induce their seizures
  • CDKL5 deficiency disorder, a type of encephalopathy that causes seizures and other symptoms

Before Taking

You should not take this medication if you have had an adverse reaction to it in the past.

According to the manufacturer, an echocardiogram is recommended before, during, and after treatment with Fintepla.


Some conditions may increase the risk of adverse effects due to taking Fintelpa. Be sure to tell your healthcare provider if you are pregnant or plan to become pregnant or breastfeed while using this medication.

Tell your practitioner if you have certain health conditions, including:

  • Mood disorders
  • A history of suicidal thoughts
  • Heart problems
  • Liver problems
  • Kidney disease
  • Glaucoma

Your healthcare provider might take extra precautions, such as monitoring frequently for adverse effects if you have one or more of these conditions.


All doses are provided by the manufacturer. This medication comes as an oral solution with a concentration of 2.2 milligrams (mg) per milliliter (mL).

According to the manufacturer, Fintepla should be started at a dose of 0.1 mg per kilogram (kg) of body weight twice per day. It can be gradually increased if needed up to a maximum recommended dose of 0.35 mg/kg twice daily (maximum daily dose of 26 mg).

Generally, for the treatment of refractory epilepsy, an anticonvulsant dose is increased gradually until seizures are well controlled, while at the same time, side effects are carefully monitored. Medication may need to be discontinued if the side effects are intolerable.


If you're also taking stiripentol and clobazam with Fintepla, the recommended maximum daily dose of Fintepla is 0.2 mg/kg twice daily (maximum daily dosage of 17 mg).

How to Take and Store

This medication should be taken at the same time every day and it can be taken with or without food.

Store the bottle and syringe together and away from the reach of children and pets. Clean the syringe after use.

The bottle should be stored at room temperature between 20° Celsius (C) to 25°C (68°Fahrenheit (F) to 77°F). You can take it out in temperatures between 15°C to 30°C (59°F to 86°F) Do not refrigerate or freeze.

Discard any unused portion of the medication three months after opening the bottle.

Side Effects

This medication can cause side effects, some of which may be severe or require treatment.

Dravet syndrome is characterized by difficulty communicating and cognitive impairment. It might be difficult for a person who is taking Fintelpa to recognize or complain about the side effects. If your child is taking this medication, it is important to familiarize yourself with the potential side effects so you can recognize them if they occur.

The most common side effects include:

  • Diminished appetite, weight loss
  • Extreme sleepiness and low energy
  • General weakness
  • Diarrhea, vomiting, or constipation
  • Problems with balance and walking, falling
  • High blood pressure
  • Drooling
  • Fever, upper respiratory infection

Appetite loss can pose a problem for children who have Dravet syndrome, especially for those who have severe cognitive deficits. You may need to talk to your child's doctor about ways to improve nutrition.


Potential serious side effects include:

  • Valvular heart disease
  • Pulmonary hypertension
  • Status epilepticus
  • Suicidal thoughts or behavior
  • Serotonin syndrome
  • Glaucoma

If you or your child is prescribed fenfluramine, it is important that you go to your healthcare provider regularly so that you can be monitored closely. This can help identify serious side effects early on, providing an opportunity for effective treatment.


This drug shouldn't be taken within 14 days of taking drugs in the monoamine oxidase inhibitor (MAOI) class, as it can lead to a dangerous interaction.

Combining fenfluramine with general anesthesia may increase cardiac risks, which could require extra monitoring during surgery.

Fenfluramine may interact negatively with certain drugs, including:

  • Coadministration with rifampin or strong CYP1A2 and CYP2B6 inducers will decrease fenfluramine plasma concentrations
  • Cyproheptadine and potent 5-HT1A, 5-HT1D, 5-HT2A, and 5-HT2C serotonin receptor antagonists may decrease the efficacy
  • Concomitant administration of FINTEPLA and drugs (e.g., SSRIs, SNRIs, TCAs, MAO inhibitors, trazodone, etc.), over-the-counter medications (eg, dextromethorphan), or herbal supplements (e.g., St. John’s Wort) that increase serotonin may increase the risk of serotonin syndrome

A Word From Verywell

When you have a medical condition for which there is no effective treatment, such as refractory epilepsy, it can feel overwhelming and hopeless at times. Medication is part of the management of Dravet syndrome. You and your family may also benefit from working with a social worker, joining a support group, physical therapy, and recreational activities that can accommodate people who are living with Dravet syndrome.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Fintepla label. June 2020.

  2. Patel M, Daboul J, Iftikhar S, Burmeister C, Ambati A, Moukarbel G, Assaly R. Weight loss supplement-induced pulmonary hypertension: A decades delayed presentation of fenfluramine-phentermine. Am J Ther. 2021 Jun 1. doi:10.1097/MJT.0000000000001387

  3. Geenen KR, Doshi SP, Patel S, Sourbron J, Falk A, Morgan A, Vu U, Bruno PL, Thiele EA. Fenfluramine for seizures associated with Sunflower syndrome. Dev Med Child Neurol. 2021 Jul 3. doi:10.1111/dmcn.14965

  4. Devinsky O, King L, Schwartz D, Conway E, Price D. Effect of fenfluramine on convulsive seizures in CDKL5 deficiency disorder. Epilepsia. 2021 Jul;62(7):e98-e102. doi:10.1111/epi.16923

Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.