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Generic name: amifampridineAM-i-FAM-pri-deen ]
Drug class: Cholinergic muscle stimulants

Medically reviewed by on Jan 24, 2022. Written by Cerner Multum.

What is Firdapse?

Firdapse is used to treat Lambert-Eaton myasthenic syndrome in adults.

Firdapse may also be used for purposes not listed in this medication guide.


Firdapse can cause seizures, even if you have never had a seizure in the past. Stop taking this medicine and call your doctor right away if you have a seizure.

Before taking this medicine

You should not use Firdapse if you are allergic to it, or if:

  • you have had a seizure in the past; or

  • you are allergic to dalfampridine.

Tell your doctor if you have ever had:

  • a seizure;

  • liver disease;

  • kidney disease; or

  • if you also take a form of Firdapse obtained from a compounding pharmacy (3,4-diaminopyridine or 3,4-DAP).

Tell your doctor if you are pregnant or breast-feeding.

How should I take Firdapse?

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

You may take Firdapse with or without food.

Do not take more than 2 tablets at one time. Do not take more than 8 tablets in 24 hours.­

The Firdapse tablet may be split in half if needed.

Store at room temperature away from moisture and heat.

Throw away any Firdapse not used before the expiration date on the medicine label.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

What happens if I overdose?

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

What should I avoid while taking Firdapse?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Firdapse side effects

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

Firdapse can cause seizures, even if you have never had a seizure in the past.

Stop using Firdapse and call your doctor at once if you have a seizure.

Common side effects of Firdapse may include:

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.

What other drugs will affect Firdapse?

Firdapse can cause seizures, especially if you also use certain medicines for infections, asthma, depression, mental illness, attention deficit disorder, or severe pain.

Many drugs can affect Firdapse. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.