Compare Tamiflu vs. Relenza

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

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Tamiflu (oseltamivir)

Prescription only

Relenza (zanamivir)

Prescription only
Treats and prevents the flu.

Tamiflu (oseltamivir) is effective at treating the flu virus, but can cause stomach side effects like nausea, vomiting, and diarrhea.

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.

Upsides
  • On average, Tamiflu (oseltamivir) reduces symptoms of the flu by 1.3 days.
  • The pill form is available as a generic.
  • The brand is available in 2 different forms: capsule and liquid.
  • Can be used for treatment in children 2 weeks of age and older.
  • Tamiflu (oseltamivir) is taken for a short period of time to treat the flu: twice a day for 5 days.
  • Relenza (zanamivir) is a great choice for people you don't like swallowing pills.
Downsides
  • Tamiflu (oseltamivir) is not a substitute for the annual flu shot.
  • Not recommended for people with kidney problems.
  • Must be taken within 2 days of contact with an infected person, or signs of flu symptoms for Tamiflu (oseltamivir) to be effective.
  • If you have HIV, you need to be on antiviral treatment at the same time as Tamiflu (oseltamivir) to decrease the chances of drug resistance by the HIV virus.
  • 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.
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Used for
  • Flu virus types A and B
  • Flu virus types A and B prevention
  • Bird flu
  • Bird flu prevention
  • Flu prevention
  • Flu treatment
Dosage forms
  • Pill
  • Liquid
  • Inhaler
Price
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Reviews
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Side effects
4possible side effects
  • Headache
    17%
  • Nausea
    8%
  • Pain
    4%
  • Vomiting
    2%
See more detailed side effects
9possible side effects
  • Diarrhea
    3%
  • Nausea
    3%
  • Sinus infection
    3%
  • Headaches
    2%
  • Nasal symptoms
    2%
  • Bronchitis
    2%
  • Cough
    2%
  • Sore throat
    2%
  • Dizziness
    2%
See more detailed side effects
Risks and risk factors
  • Delirium and abnormal behavior
    • Children
  • Severe skin reactions
    • Prior severe allergic reaction to Tamiflu (oseltamivir)
  • Hypersensitivity (allergic) reactions
    • Prior severe allergic reaction to Tamiflu (oseltamivir)
  • Reaction with vaccines
  • Bacterial infections
  • Fructose intolerance
See more detailed risks and warnings
  • 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