The amantadine dosing guidelines your healthcare provider will follow depend on factors such as your age, the condition being treated, and other medications you are taking. For children under the age of nine, the dosage will be based on weight. Amantadine is typically taken once or twice a day, and you should not adjust your amantadine dose unless your healthcare provider specifically instructs you to do so.
The dose of amantadine hydrochloride (Symmetrel®) that your healthcare provider recommends will vary, depending on a number of factors, including:
- The condition being treated
- Your age
- Your weight (for children)
- Your kidney and liver function
- Other medications you are taking.
As always, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
The recommended dose of amantadine for treating or preventing the flu in adults is amantadine 100 mg twice daily or 200 mg once daily (taking it twice a day may decrease the chance of amantadine side effects). A lower dose (amantadine 100 mg once daily) is recommended for people age 65 or older.
For children age nine and older, the recommended dose is amantadine 100 mg twice daily. For children ages one to eight, the recommended dose is based on weight -- amantadine 2 mg to 4 mg per pound per day, not to exceed 150 mg per day.
For flu treatment, the drug should be started as soon as possible, within 24 to 48 hours of the start of flu symptoms, and should be continued for 24 to 48 hours after the symptoms go away. For flu prevention, amantadine is usually given along with a flu shot (it should not be used in this way with the intranasal flu vaccine). In this case, amantadine should be continued for two to four weeks after the vaccine, as it takes time for the vaccine to start working. If a flu shot is not available or cannot be taken for various reasons, the drug should be continued as long as the flu virus is still in your community. In all cases, amantadine should be taken for at least 10 days after any known exposure to the flu virus.