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Antiviral for H1N1

What is Influenza?

Influenza or ‘flu’ is an infection caused by the influenza virus. Influenza A in particular is caused by the H1N1 virus.

How Does Influenza Spread?

The H1N1 virus spreads through air where droplets from an infected person’s cough or sneeze inhaled by an uninfected individual, or through physical contact with infected hands or surfaces.

Signs And Symptoms Of Suspected H1N1 Influenza Infection

  • Fever of more than 38°C, and
  • Respiratory signs and symptoms (dry cough, sore throat, difficulty in breathing, nasal congestion/blockage), and
  • Tiredness, joint/muscle pain, headache, vomiting and fits (in infants), and
  • Diarrhea and conjunctivitis

How You Can Be Infected

Close contact with a person diagnosed with influenza within 10 days of the onset of the symptoms or recent history of travel to areas reporting cases of influenza.

Symptomatic Relief

    1. Take analgesic/anti-fever medication such as paracetamol; the recommended dose is as follows;

Adult :

      • 500mg – 1000mg every 4 – 6 hours, maximum 4g daily


      • Child up to 1 year: 60 – 120mg/dose
      • Child 1- 5 years: 120 – 240 mg/dose
      • Child 6 – 12 years: 240 – 480mg/dose
      *repeat every 4 – 6 hours when necessary, maximum of 4 doses in 24 hours
  1. Currently there are 2 types of antiviral medication available for treatment of influenza in the Ministry of Health Malaysia namely oseltamivir as first line treatment and zanamivir as an alternative treatment.

All Antiviral Drugs Must Be Prescribed By Doctors

Treatment with Antiviral Drugs: Indications, Doses & Side Effects

Both antivirals are used to to treat and prevent influenza.

Use in treating influenza

The medicines are intended to shorten the duration of having symptoms, such as fever, headache, muscles ache, cough and sore throat. It is advisable to start treatment early, within 48 hours of the onset symptoms. The earlier treatment starts, the shorter and less severe the illness.

Use in preventing influenza

The medicines are not recommended for routine prophylaxis against influenza; immunization is recommended to prevent infection. However, they can be use in poorly vaccinated communities at risk, such as when it is necessary to stop the institutional outbreak.

Treatment & Doses

Children: (>1 year according to their weight)

Body Weight in kg
Recommended dose for 5 days
< 15 kg 30 mg twice daily
15 to 23 kg 45 mg twice daily
23 to 40 kg 60 mg twice daily
> 40 kg 75 mg twice daily

Adult & adolescents > 13 yrs :
75 mg twice daily for 5 days

  • Oseltamivir capsule 75 mg
  • Powder for oral suspension 12mg/ml
  • Powder for oral suspension 60mg/5ml
Children: 5 years , 10 mg (2 puffs) twice daily for 5 days
Adult: 10mg (2 puff) twice daily, for 5 days

  • Zanamivir inhalation disk —5mg/puff

How to administer: The antiviral may be taken with or without food, but the chance of getting stomach upset can be reduced if taken with food or milk. For oral suspension, reconstitution method is as follows:

    Tap the bottle to loosen the powder.

  • Add the amount of water specified on the bottle
  • Shake well for 15 seconds
  • Following the reconstitution direction, oseltamivir oral suspension contains 12mg of osetalmivir per ml

Missed dose: If a dose is missed:

  • Take as soon as you remember.
  • If it is almost time for the next dose, skip the dose you missed and take the next dose.
  • Do not take a double dose to make up for the dose that you missed

Side-effects: Common side effects of antiviral medication include nausea, vomiting, stomach pain, diarrhea and headache. However zanamivir may cause bronchospasm (breathing problems), cough and nasal congestion. Immediately seek medical advice in case of suspected side effects.

Best Practices in management of influenza:

  • Drink lots of water
  • Get adequate rest
  • Avoid alcohol consumption and cigarette smoking
  • Limit your journey or visits to places with known cases of influenza
  • Use face mask whenever possible
  • Practice hand washing especially after coughing or sneezing
  • Avoid crowded places


  • Store at room temperature and away from excessive heat and moisture
  • Keep the suspension in the refrigerator and do not freeze
  • Throw away any unused suspension after 10 days and any expired medication
  • Keep out of reach and sight of children.

Precautions, please tell your doctor:

  • If you are allergic to oseltamivir or zanamivir
  • If you are taking other medicines, including those you have bought without prescription including traditional medicines
  • If you have problems with your kidneys, heart, liver or lungs diseases, HIV or AIDS
  • If you are pregnant, plan to become pregnant or breast-feeding
  • As for zanamivir, please tell your doctor if you are asthmatic or having breathing problems

Make sure to read and understand the product leaflet

  • If you have any questions, please ask your pharmacist or doctor
  • Do not share the medicine with others, even though the symptoms are the same as yours.
  • Do not stop taking your medication, or change the dose, without first checking with your doctor
  • Do not use the medication to treat any other complaints.


Last reviewed : 20 March 2015
Writer : Siti Nurul Fathihah bt. Baharudin
Reviewer : Yam Chiew Fong