In the U.S.—

• Antiviral, systemic

Rimantadine (ri-MAN-ta-deen) is an antiviral. It is used to prevent or treat certain influenza (flu) infections (type A). It may be given alone or along with flu shots. Rimantadine will not work for colds, other types of flu, or other virus infections.

Rimantadine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Syrup (U.S.)
• Tablets (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For rimantadine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to rimantadine or amantadine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in humans. However, studies in some animals have shown that rimantadine is harmful to the fetus and causes birth defects.

Breast-feeding—It is not known if rimantadine passes into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children—This medicine has been tested in children over one year of age and has not been shown to cause different side effects or problems in these children than it does in adults. There is no specific information comparing the use of rimantadine in children under one year of age with use in other age groups.

Older adults—Elderly people are especially sensitive to the effects of rimantadine. Difficulty in sleeping, difficulty in concentrating, dizziness, headache, nervousness, and weakness may be especially likely to occur. Stomach pain, nausea, vomiting, and loss of appetite may also occur.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

• Epilepsy or other seizures (history of)—Rimantadine may increase the frequency of convulsions (seizures) in patients with a seizure disorder

• Kidney disease—Rimantadine is removed from the body by the kidneys; patients with severe kidney disease will need to receive a lower dose of rimantadine

• Liver disease—Patients with severe liver disease may need to receive a lower dose of rimantadine

Talk to your doctor about the possibility of getting a flu shot if you have not had one yet.

This medicine is best taken before exposure, or as soon as possible after exposure, to people who have the flu.

To help keep yourself from getting the flu, keep taking this medicine for the full time of treatment.

If you already have the flu, continue taking this medicine for the full time of treatment even if you begin to feel better after a few days. This will help to clear up your infection completely. If you stop taking this medicine too soon, your symptoms may return. This medicine should be taken for at least 5 to 7 days.

This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times day and night.

If you are using the oral liquid form of rimantadine, use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

Dosing—

The dose of rimantadine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of rimantadine. Your dose may be different if you have kidney disease or liver disease. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage forms (syrup, tablets):
  • For the prevention or treatment of flu:
    • Elderly adults—100 milligrams (mg) once a day.
    • Adults and children 10 years of age and older—100 mg two times a day.
    • Children up to 10 years of age—5 mg per kilogram (2.3 mg per pound) of body weight once a day. Children in this age group should not receive more than 150 mg a day.

Missed dose—

If you do miss a dose of this medicine, take it as soon as possible. This will help to keep a constant amount of medicine in the blood. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Keep the syrup form of this medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

This medicine may cause some people to become dizzy or confused, or to have trouble concentrating. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or confused. If these reactions are especially bothersome, check with your doctor.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Difficulty in concentrating;  dizziness ;  dryness of mouth;  headache ;  loss of appetite;  nausea ;  nervousness;  stomach pain ;  trouble in sleeping;  unusual tiredness;  vomiting 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.