Amantadine hydrochloride (
Symmetrel®) is a prescription medication approved for the following uses:
Side Effects of Amantadine
As with any medicine, side effects are possible with amantadine. However, not everyone who takes the drug will experience side effects. If side effects do occur, in most cases, they are minor and either require no treatment or can easily be treated by you or your healthcare provider. Serious side effects are less common.
Common side effects include but are not limited to:
- Nausea
- Dizziness or lightheadedness
- Insomnia.
(Click Amantadine Side Effects to learn more, including potentially serious side effects you should report immediately to your healthcare provider.)
What Should I Tell My Healthcare Provider?
You should talk with your healthcare provider prior to taking amantadine if you have:
- A psychiatric disorder or a history of substance abuse
- Congestive heart failure (CHF)
- Glaucoma (an eye condition)
- Low blood pressure (hypotension)
- Swelling in the hands, feet, or ankles (edema)
- Seizures or epilepsy
- Liver disease, such as liver failure, cirrhosis, or hepatitis
- Kidney disease, including kidney failure (renal failure)
- Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about any other medications you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
The dose of amantadine 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.
What If I Take an Overdose of Amantadine?
An overdose of amantadine can be quite dangerous -- even life-threatening. If you happen to take too much, seek immediate medical attention.
How Should Amantadine Be Stored?
Amantadine should be stored at room temperature, away from moisture and heat. Keep the drug in an airtight container.
Keep this and all other medications out of the reach of children.
What Should I Do If I Miss a Dose?
If you miss a dose of amantadine, take the missed dose as soon as you remember and then continue with your regular schedule. However, if it is almost time for your next dose, skip the missed dose and continue as directed. Do not take a double dose.
How Does Amantadine Work?
Amantadine may work for
the flu by inhibiting the uncoating of the
flu virus, an important step in the replication (the "reproduction") of the virus. Specifically, it inhibits the activity of the
influenza virus M2 protein, which forms a channel in the virus membrane. As a result, the virus cannot replicate (make copies of itself) after it enters a human cell.
Amantadine is effective only for some
influenza A viruses and is not effective against influenza B viruses. Because the "
bird flu" or "
avian flu" virus (
H5N1) is a type of influenza A, the medication may work for some strains of this virus. However, many strains of H5N1 influenza are resistant to it.
For any given year, the predominant flu strain may or may not be susceptible to amantadine. If the predominant flu strain is not susceptible, this medication should not be used to prevent or treat the flu.
It is not known exactly how the medication works for
Parkinson's disease and other similar conditions or movement disorders. Amantadine is known to affect several different brain chemicals, including dopamine and NMDA (N-methyl D-aspartate).
Some general considerations for when and how to take amantadine include the following:
- The medication comes in the form of a tablet and syrup (the generic version is also available as a capsule). It is usually taken by mouth once or twice a day.
- You can take amantadine with or without food. If the medication bothers your stomach, try taking it with food.
- For treating the flu, amantadine works better the earlier it is started. Ideally, it should be started within 24 to 48 hours of the onset of flu symptoms.
- For the medication to work properly, it must be taken as prescribed. Amantadine will not work if you stop taking it or stop taking it too soon.
Brand-name amantadine is manufactured by Endo Pharmaceuticals, Inc. Generic versions of the drug are made by various manufacturers.
Amantadine is available in the following strengths and forms:
- Amantadine 100 mg tablets
- Amantadine 50 mg/5 mL syrup, which contains 50 mg of medication per 5 mL (per teaspoonful) and is raspberry-flavored.
Generic amantadine (but not the brand-name version) also comes in capsule form (100 mg).
Is There a Generic Version of Amantadine?
Currently, generic amantadine tablets, capsules, and syrup are available
(see Generic Symmetrel).
