Compare Relenza vs. Symmetrel

Head-to-head comparisons of medication uses, side effects, ratings, and more.


Relenza (zanamivir)

Prescription only

Symmetrel (amantadine)

Prescription only
Prevents and reduces the symptoms of the flu.

Relenza (zanamivir) can reduce flu symptoms for people 7 years & older, but they should take it within two days of the flu starting or it won't work.

Treats Parkinson's disease, the flu, and side effects from antipsychotic drugs.

Symmetrel (amantadine) is a generic medicine that can be used alone, or with other medicines to treat early Parkinson's disease.

  • Relenza (zanamivir) is a great choice for people you don't like swallowing pills.
  • Symmetrel (amantadine) can be taken by itself or with other medicines to treat the symptoms of early Parkinson's disease, including muscle spasms, tremors, and difficulty with movements.
  • Symmetrel (amantadine) is available in generic and in both a pill and liquid form.
  • Compared to other medicines for Parkinson's disease, the side effects are relatively mild.
  • Start Relenza (zanamivir) within 2 days of getting the flu or else the medicine won't work.
  • Taking Relenza (zanamivir) won't stop you from being contagious.
  • Relenza (zanamivir) is inhaled so people with breathing problems shouldn't take it.
  • Symmetrel (amantadine) sometimes has to be taken multiple times a day.
  • Symmetrel (amantadine) can’t stop or cure Parkinson's disease. It can only slow down the progression.
  • You can't take certain forms of the flu vaccine if you're taking Symmetrel (amantadine). Talk to your doctor before receiving vaccines.
  • You can't stop taking Symmetrel (amantadine) suddenly without talking to your doctor since your Parkinson's can get worse.
Used for
Dosage forms
  • Inhaler
  • Pill
  • Liquid
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Side effects
9possible side effects
  • Diarrhea
  • Nausea
  • Sinus infection
  • Headaches
  • Nasal symptoms
  • Bronchitis
  • Cough
  • Sore throat
  • Dizziness
See more detailed side effects
The Symmetrel (amantadine) FDA package insert doesn’t have numbers about how common side effects are.
Risks and risk factors
  • Nasal flu vaccine won't work
    • Had nasal flu vaccine within last two weeks
  • Unusual behavior
  • Breathing problems
    • Asthma
    • COPD
  • Severe allergic reactions
    • Prior severe allergic reaction to Relenza (zanamivir)
See more detailed risks and warnings
  • Deaths from overdosage
    • Kidney damage or failure
  • Higher risk of suicide
    • Taking Symmetrel (amantadine) for the flu
  • Higher risk of seizures
    • History of seizures
  • Heart failure
    • Heart failure
    • History of swelling in the arms or legs
  • Lack of impulse control
    • Taking other medicines for Parkinson's disease
See more detailed risks and warnings