SEASONAL INFLUENZA
Influenza antiviral medications
What are “antiviral” medications?
Antiviral medications can stop or slow down the action of viruses. They can be used to help prevent influenza. They can also help shorten the length of time a person has the illness and lessen its severity. The two most commonly used antiviral medications in Alberta are amantadine (for example, Symmetrel®) and oseltamivir (for example, Tamiflu®).
When are antiviral medications used to PREVENT influenza?
Some people may be at risk of getting serious complications from influenza but cannot be vaccinated, for example, because of an allergy to eggs. A doctor may prescribe an antiviral drug to give these individuals some protection during the influenza season.
Doctors may also prescribe antiviral medications for people at high risk if:
- They need extra protection, even though they were immunized.
- They were immunized after the influenza virus appeared in the community (to help protect them until the vaccine becomes effective).
- The strain of the influenza virus circulating in the community is different from the vaccine strains.
They may also be prescribed for people who have not been immunized and are in contact with those who are at high risk.
When are antiviral medications used to TREAT influenza?
A doctor may prescribe antiviral medications when a person at risk comes down with influenza. To be effective, medication must be started within 48 hours after the first symptom appears. They are usually given for five days.
Amantadine only works against influenza Type A virus. Unfortunately, some viruses have become resistant to it. Amantadine can be given to children over the age of one year. However, it cannot be given with certain medications or to people with certain health problems. Possible side effects include nausea, blurred vision, dizziness, difficulty sleeping, decreased appetite, anxiety, confusion, dry mouth, headache and constipation. These may go away during treatment. In older people, amantadine can cause more serious side effects, especially on the nervous system.
Oseltamivir, a newer antiviral medication, is effective against both influenza Type A and influenza Type B. It can be used for children over the age of one year. Oseltamivir can cause nausea, vomiting and dizziness, but these side effects may be lessened if this medication is taken with food.
