Fenfluramine

Fenfluramine is used to treat seizures from Dravet syndrome and Lennox-Gastaut syndrome in individuals who are at least 2 years old.

Fenfluramine can lead to serious side effects affecting your heart and lungs. fenfluramine is only available through a special program. You must be registered in this program and fully understand the risks and benefits of this medicine.

Fenfluramine may also be used for reasons not mentioned in this medication guide.

Your doctor will do tests to ensure you do not have any conditions that would make it unsafe for you to use fenfluramine.

Follow all instructions on your prescription label and read all medication guides or instruction sheets. Your doctor may change your dose from time to time. Use the medicine exactly as directed.

Fenfluramine may be habit-forming. Misuse can lead to addiction, overdose, or death. Keep the medicine in a place where others cannot access it. Selling or giving away fenfluramine is illegal.

Read and carefully follow any Instructions for Use that come with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

You can take fenfluramine with or without food.

Measure liquid medicine carefully. Use the dosing syringe provided, or a medicine dose-measuring device (not a kitchen spoon).

Follow your healthcare provider's instructions for giving fenfluramine through a feeding tube if necessary.

Fenfluramine may cause a decreased appetite and weight loss. Weigh yourself regularly and inform your doctor if you lose weight. You may need to stop taking fenfluramine if you lose too much weight. Weight loss can affect growth in children.

Your heart function will need to be monitored with an electrocardiograph or ECG (sometimes called an EKG).

Store at room temperature away from moisture and heat. Do not refrigerate or freeze this medicine. Keep the bottle and syringe together in a clean area.

Keep track of your medicine. You should know if anyone is using it improperly or without a prescription.

Dispose of any unused fenfluramine 3 months after you first opened the bottle or after the "discard" date on the label, whichever is sooner.

Do not stop using fenfluramine suddenly, even if you feel fine. Stopping suddenly may lead to increased seizures. Follow your doctor's instructions for tapering your dose.

Do not use fenfluramine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could happen. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, and tranylcypromine. Wait at least 14 days after stopping an MAO inhibitor before you take fenfluramine.

Fenfluramine can cause serious side effects affecting your heart and lungs. Call your doctor immediately if you experience: chest pain, shortness of breath, unusual tiredness, swelling in your lower legs, fast or pounding heartbeats, blue skin or lips, or if you feel light-headed.

Fenfluramine may lead to weight loss, which could impact growth in children. Weigh yourself regularly and inform your doctor if you lose weight. You may need to stop taking fenfluramine if you lose too much weight.

Avoid driving or engaging in hazardous activities until you know how fenfluramine will affect you. Your reactions might be affected.

Some people may have thoughts about suicide while taking fenfluramine. Be aware of changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

You should not use fenfluramine if you are allergic to it.

Do not use fenfluramine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could happen. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

Tell your doctor if you have ever had:

• heart problems;
• weight loss;
• depression, a mood disorder, or suicidal thoughts or actions;
• a drug or alcohol addiction; or
• liver or kidney disease.

Some people have thoughts about suicide while taking fenfluramine. Your doctor will need to check your progress during regular visits. Your family or other caregivers should also watch for changes in your mood or symptoms.

Tell your doctor if you are also using stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with fenfluramine could lead to a serious condition called serotonin syndrome.

Tell your doctor if you are pregnant or breastfeeding.

If you are pregnant, your name may be added to a pregnancy registry to track the effects of fenfluramine on the baby.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Report any new or worsening symptoms to your doctor, such as: changes in mood or behavior, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or harming yourself.

Fenfluramine can cause serious side effects on your heart and lungs. Call your doctor right away if you have:

• chest pain, pounding heartbeats or fluttering in your chest;
• shortness of breath;
• blue-colored skin or lips;
• swelling in your lower legs; or
• unusual tiredness or weakness, feeling like you might pass out.

Also call your doctor immediately if you have:

• loss of appetite and weight loss;
• worsening seizures;
• blurred vision, tunnel vision, eye pain or redness, or seeing halos around lights;
• nausea or vomiting; or
• increased blood pressure—severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Fenfluramine can affect weight or growth in children. Tell your doctor if your child is not growing at a normal rate while taking this medicine.

Common side effects of fenfluramine may include:

• increased blood pressure;
• drowsiness;
• decreased weight;
• loss of appetite, vomiting, diarrhea, constipation;
• seizures that do not stop;
• feeling weak or tired;
• fever, infections;
• abnormal heart function tests;
• problems with balance, walking, or muscle movement;
• drooling; or
• cold symptoms such as stuffy nose, sneezing, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Take the medicine as soon as you can, but skip the missed dose if it is close to the time for your next dose. Do not take two doses at the same time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

• Avoid driving or hazardous activity until you know how fenfluramine will affect you. Your reactions could be impaired.

• Avoid taking an herbal supplement containing St. John's wort.

Sometimes, using certain medicines together can be unsafe. Some drugs can change the levels of other drugs in your blood, which may lead to more side effects or make the medicines work less well.

Tell your doctor about all the other medicines you are taking, especially:

• stiripentol; or
• clobazam.

This list is not complete. Other drugs may affect fenfluramine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.