Amantadine or Rimantadine for Influenza (Flu)
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How It Works
These antiviral medicines prevent the spread of type A influenza by interfering with the production of the virus inside the body. They do not treat or protect you against influenza B.
Why It Is Used
These antiviral medicines may reduce the severity of influenza (flu) symptoms and shorten the course of the illness of influenza A.1 They need to be started within 48 hours of the first symptoms and continued, usually, for 7 days.
For the past few years, the U.S. Centers for Disease Control and Prevention (CDC) have advised doctors not to use amantadine or rimantadine (Flumadine) to treat or prevent the flu. These medicines have not worked against most types of the flu virus. Talk to your doctor about the medicine that is best to use for the current type of flu.
When used to protect people during a flu outbreak, antiviral medicines usually are used for 7 days but may be continued for 5 to 7 weeks.
How Well It Works
Amantadine and rimantadine can relieve or prevent symptoms of influenza A if taken soon after infection. But these antiviral medicines do not always treat or prevent the flu.2
When given within 48 hours after symptoms begin, they may reduce symptoms, shorten the length of influenza A illness by 1 or 2 days, and allow for a faster return to usual activities.
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
- Usually the benefits of the medicine are more important than any minor side effects.
- Side effects may go away after you take the medicine for a while.
- If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.
Call 911 or other emergency services right away if you have:
- Trouble breathing.
- Swelling of your face, lips, tongue, or throat.
- A seizure.
Call your doctor right away if you have:
- Blurred vision.
- Confusion, hallucinations, or sudden changes in behavior.
Common side effects of these medicines include:
- Trouble sleeping.
- Nausea and vomiting.
- Sleepiness or dizziness.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Amantadine and rimantadine are effective only against some type A influenza viruses.
Amantadine usually should not be taken at the same time as antihistamines or other medicines that stimulate the central nervous system. These may increase the risk of side effects such as insomnia, anxiety, and, at high doses, seizures.
Amantadine is removed from the body by the kidneys. Rimantadine is removed by the liver. This difference may have an impact on which medicine is used to treat people who have diseases affecting the kidneys or liver. Because side effects occur less often with rimantadine, it may be a better choice.
Little information exists regarding how well antiviral medicines work for treating children who have influenza A.
- Amantadine is used to prevent and treat type A influenza in adults and in children older than age 1.
- Rimantadine is used to prevent and treat type A influenza in adults. But in children it is used only to prevent influenza A.
Antiviral medicines may need to be given only once a day in older adults.
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
Advice for women
If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
- Fiore AE, et al. (2011). Antiviral agents for the treatment and chemoprophylaxis of influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 60(1): 1–25.
- Centers for Disease Control and Prevention (2006). CDC Health Alert: CDC Recommends Against the Use of Amantadine and Rimantadine for the Treatment or Prophylaxis of Influenza in the United States During the 2005–06 Influenza Season. Available online: http://www.cdc.gov/flu/han011406.htm.
Last Revised: July 9, 2012
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