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Amifampridine Side Effects

Medically reviewed by Last updated on Jun 8, 2022.

For the Consumer

Applies to amifampridine: oral tablet

Side effects requiring immediate medical attention

Along with its needed effects, amifampridine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking amifampridine:

More common

  • Arm or leg pain
  • bladder pain
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bloody or cloudy urine
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chest pain
  • chills
  • cough
  • cough producing mucus
  • diarrhea
  • difficult, burning, or painful urination
  • difficulty breathing or swallowing
  • dizziness
  • fever
  • frequent urge to urinate
  • general feeling of discomfort or illness
  • headache
  • hoarseness
  • joint pain
  • loss of appetite
  • lower back or side pain
  • muscle pains, spasms, or weakness
  • nausea
  • nervousness
  • pounding in the ears
  • rapid weight gain
  • runny nose
  • shivering
  • slow or fast heartbeat
  • sneezing
  • sore throat
  • sweating
  • swollen, painful, or tender lymph glands in the neck, armpit, or groin
  • tightness of the chest
  • trouble sleeping
  • unusual tiredness or weakness
  • unusual weight gain or loss
  • vomiting

Side effects not requiring immediate medical attention

Some side effects of amifampridine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Back pain
  • blindness
  • constipation
  • decreased vision
  • discouragement
  • falls
  • feeling cold
  • feeling sad or empty
  • heartburn
  • irritability
  • lack or loss of strength
  • loss of interest or pleasure
  • pale skin
  • stomach pain
  • trouble concentrating
  • troubled breathing with exertion
  • unusual bleeding or bruising

For Healthcare Professionals

Applies to amifampridine: oral tablet


Common (1% to 10%): Lymphadenopathy[Ref]


Common (1% to 10%): Viral infection[Ref]


Very common (10% or more): Back pain (14%), muscle spasm (12%), muscle weakness (10%), pain in extremity (10%)

Common (1% to 10%): Blood creatine phosphokinase increased[Ref]


Very common (10% or more): Cataract (10%)

Frequency not reported: Blurred vision[Ref]


Common (1% to 10%): Peripheral edema

Uncommon (0.1% to 1%): Hypercholesterolemia[Ref]


Common (1% to 10%): Insomnia, depression

Frequency not reported: Sleep disorders, anxiety[Ref]


Common (1% to 10%): Urinary tract infection[Ref]


Very common (10% or more): Elevated liver enzymes (e.g., elevated alanine aminotransferase [ALT], aspartate aminotransferase [AST], lactate dehydrogenase [LDH], gamma-glutamyl transferase [GGT] (14%)

transferase (GGT)[Ref]


Very common (10% or more): Upper respiratory tract infection (33%)

Common (1% to 10%): Bronchitis, dyspnea, influenza

Frequency not reported: Bronchial hypersecretion, asthma attack in asthmatic patients or patients with a history of asthma, cough[Ref]


Common (1% to 10%): Fall, pyrexia[Ref]

Nervous system

Very common (10% or more): Paresthesia/dysesthesia (i.e., oral paresthesia, oral hypoesthesia) (69%), headache (14%), dizziness (10%), asthenia (10%)

Common (1% to 10%): Seizures[Ref]


Very common (10% or more): Hypertension (12%)

Frequency not reported: Raynaud's syndrome, cardiac rhythm disorders, palpitations[Ref]


Very common (10% or more): Hyperhidrosis, cold sweat

Common (1% to 10%): Erythema[Ref]


Very common (10% or more): Abdominal pain (14%), nausea (14%), diarrhea (14%), dyspepsia (17%)

Common (1% to 10%): Constipation, GI reflux

Frequency not reported:: Epigastralgia[Ref]

Frequently asked questions


1. "Product Information. Firdapse (amifampridine)." Catalyst Pharmaceuticals, Inc. (2018):

2. "Product Information. Ruzurgi (amifampridine)." Medunik Canada (2021):

Further information

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

Some side effects may not be reported. You may report them to the FDA.