Last updated on RxList: 1/2/2018
Flumadine Side Effects Center

Last reviewed on RxList 1/02/2018

Flumadine (rimantadine hydrochloride) is an antiviral medication used to treat and prevent influenza A (a viral infection) in adults and in children. There may be some flu seasons during which Flumadine is not recommended because certain flu strains may be resistant to this drug. Flumadine is available in generic form. Common side effects of Flumadine include trouble sleeping (insomnia), nausea, vomiting, loss of appetite, stomach pain, diarrhea, dry mouth, weakness, dizziness, drowsiness, nervousness, headache, anxiety, or trouble concentrating.

The recommended adult dose of Flumadine is 100 mg twice a day. The pediatric dose is 5 mg/kg but not exceeding 150 mg, once daily. Flumadine may interact with cimetidine, aspirin, acetaminophen, or nasal flu vaccine. Tell your doctor all medications and supplements you use. Flumadine should be used only when prescribed during pregnancy. It is unknown if this medication passes into breast milk. Similar drugs pass into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding.

Our Flumadine (rimantadine hydrochloride) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Which illness is known as a viral upper respiratory tract infection? See Answer
Flumadine Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • extreme drowsiness, or if you fall asleep suddenly even after feeling alert;
  • a light-headed feeling, like you might pass out;
  • depression, agitation, aggression, behavior changes, hallucinations, thoughts of hurting yourself; or
  • a seizure.

Side effects such as headache, dizziness, feeling weak or tired, anxiety, vomiting, and stomach pain may be more likely in older adults.

Common side effects may include:

  • nausea, vomiting, loss of appetite, stomach pain;
  • dry mouth;
  • sleep problems (insomnia); or
  • dizziness.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Flumadine (Rimantadine)


A Cold or The Flu? How to Tell the Difference See Slideshow
Flumadine Professional Information


In 1,027 patients treated with Flumadine (rimantadine) in controlled clinical trials at the recommended dose of 200 mg daily, the most frequently reported adverse events involved the gastrointestinal and nervous systems.

Incidence > 1%: Adverse events reported most frequently (1-3%) at the recommended dose in controlled clinical trials are shown in the table below.

Nervous System
  Insomnia 2.1% 0.9%
  Dizziness 1.9% 1.1%
  Headache 1.4% 1.3%
  Nervousness 1.3% 0.6%
  Fatigue 1.0% 0.9%
Gastrointestinal System    
  Nausea 2.8% 1.6%
  Vomiting 1.7% 0.6%
  Anorexia 1.6% 0.8%
  Dry mouth 1.5% 0.6%
  Abdominal Pain 1.4% 0.8%
Body as a Whole    
  Asthenia 1.4% 0.5%

Less frequent adverse events (0.3 to 1%) at the recommended dose in controlled clinical trials were: Gastrointestinal System: diarrhea, dyspepsia; Nervous System: impairment of concentration, ataxia, somnolence, agitation, depression; Skin and Appendages: rash; Hearing and Vestibular: tinnitus; Respiratory: dyspnea.

Additional adverse events (less than 0.3%) reported at recommended doses in controlled clinical trials were: Nervous System: gait abnormality, euphoria, hyperkinesia, tremor, hallucination, confusion, convulsions; Respiratory: bronchospasm, cough; Cardiovascular: pallor, palpitation, hypertension, cerebrovascular disorder, cardiac failure, pedal edema, heart block, tachycardia, syncope; Reproduction: non-puerperal lactation; Special Senses: taste loss/change, parosmia. Rates of adverse events, particularly those involving the gastrointestinal and nervous systems, increased significantly in controlled studies using higher than recommended doses of Flumadine (rimantadine) . In most cases, symptoms resolved rapidly with discontinuation of treatment. In addition to the adverse events reported above, the following were also reported at higher than recommended doses: increased lacrimation, increased micturition frequency, fever, rigors, agitation, constipation, diaphoresis, dysphagia, stomatitis, hypesthesia and eye pain.

Adverse Reactions in Trials of Rimantadine and Amantadine: In a six-week prophylaxis study of 436 healthy adults comparing rimantadine with amantadine and placebo, the following adverse reactions were reported with an incidence > 1 %.

200 mg/day
200 mg/day
Nervous System
Insomnia 3.4% 0.7% 7.0%
Nervousness 2.1% 0.7% 2.8%
Impaired Concentration 2.1% 1.4% 2.1%
Dizziness 0.7% 0.0% 2.1%
Depression 0.7% 0.7% 3.5%
Total % of subjects with adverse reactions 6.9% 4.1% 14.7%
Total % of subjects withdrawn due to adverse reactions 6.9% 3.4% 14.0%

Geriatric Use

Approximately 200 subjects over the age of 65 were evaluated for safety in controlled clinical trials with Flumadine (rimantadine hydrochloride). Geriatric subjects who received either 200 mg or 400 mg of rimantadine daily for 1 to 50 days experienced considerably more central nervous system and gastrointestinal adverse events than comparable geriatric subjects receiving placebo. Central nervous system events including dizziness, headache, anxiety, asthenia, and fatigue, occurred up to two times more often in subjects treated with rimantadine than in those treated with placebo. Gastrointestinal symptoms, particularly nausea, vomiting, and abdominal pain occurred at least twice as frequently in subjects receiving rimantadine than in those receiving placebo. The gastrointestinal symptoms appeared to be dose related. In patients over 65, the recommended dose is 100 mg, daily (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).

Read the entire FDA prescribing information for Flumadine (Rimantadine)

© Flumadine Patient Information is supplied by Cerner Multum, Inc. and Flumadine Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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