Amantadine is a medication with several distinct uses: treating symptoms of Parkinson’s disease, helping recovery after traumatic brain injury, and managing fatigue in multiple sclerosis. It was originally developed as an antiviral drug for influenza A, but widespread viral resistance has made that use largely obsolete. Today, its primary role is neurological.
Parkinson’s Disease
Amantadine’s most established use is managing the symptoms of Parkinson’s disease. It works by increasing dopamine release in the brain and preventing dopamine from being reabsorbed too quickly, which helps compensate for the dopamine shortage that drives Parkinson’s symptoms like tremor, stiffness, and difficulty with movement. The typical dose is 100 mg twice daily, though some people start at 100 mg once daily and work up from there.
Beyond treating core Parkinson’s symptoms, amantadine also addresses a frustrating side effect of other Parkinson’s medications. Long-term use of levodopa (the main drug for Parkinson’s) often causes involuntary, uncontrollable movements called dyskinesia. An extended-release form of amantadine (sold as Gocovri) is specifically approved to treat these movement problems when taken alongside levodopa.
Amantadine can also help with “off” episodes, those stretches of time when levodopa wears off between doses and movement, walking, or speaking suddenly becomes much harder. For many people with Parkinson’s, these off periods are among the most disruptive parts of daily life, and adding amantadine to their regimen can smooth out those gaps.
Drug-Induced Movement Problems
Certain psychiatric medications, particularly older antipsychotics, can cause involuntary movements like tremor, muscle rigidity, or restlessness. These are called extrapyramidal reactions, and they mimic some Parkinson’s symptoms. Amantadine is FDA-approved to treat these medication side effects, typically at 100 mg twice daily, with occasional increases up to 300 mg daily if needed.
Recovery After Traumatic Brain Injury
One of amantadine’s most compelling off-label uses is speeding recovery in people with severe traumatic brain injury. A landmark trial published in the New England Journal of Medicine found that patients given amantadine during the first four weeks after injury recovered significantly faster than those given a placebo. The amantadine group showed higher rates of recovery across all six behaviors tracked in the study, including measures of awareness, communication, and motor function. Even after the drug was stopped, recovery remained more favorable across five of those six behaviors at the six-week mark.
This finding has made amantadine a common choice in rehabilitation settings for patients who are slow to regain consciousness or function after a serious head injury. It’s not a guaranteed fix, but the evidence for accelerated recovery is strong enough that many neurologists consider it a standard part of TBI management.
Fatigue in Multiple Sclerosis
Fatigue is one of the most common and debilitating symptoms of multiple sclerosis, and amantadine at 100 mg twice daily is frequently prescribed to help. Guidelines from the German Multiple Sclerosis Society give it a strong recommendation, noting moderate improvement in subjective fatigue, concentration, memory, and problem solving compared with placebo.
The evidence here is real but mixed. In one controlled trial of 52 adults with MS-related fatigue, amantadine significantly reduced fatigue scores compared to aspirin after four weeks of treatment. However, a Cochrane review examining multiple trials found the overall quality of the research was poor, with high dropout rates and inconsistent results across studies. In practice, many neurologists still offer it as a trial option for MS fatigue since it’s generally well tolerated, but its benefits vary considerably from person to person.
Influenza A (Mostly Historical)
Amantadine was originally approved to prevent and treat influenza A infections. It works by blocking a protein the virus needs to release its genetic material inside your cells. However, nearly all seasonal influenza A viruses circulating in the United States are now resistant to amantadine, and the CDC has not recommended it for flu treatment in many years. If you’re looking for antiviral flu treatment today, newer drugs like oseltamivir (Tamiflu) are the standard choice.
Common Side Effects
Amantadine is generally well tolerated, but it does come with some notable side effects. The most distinctive is livedo reticularis, a mottled, net-like purplish discoloration of the skin, usually on the legs. Up to 40% of patients develop it. The discoloration is harmless and typically fades after stopping the medication, but it can be alarming if you’re not expecting it.
Other common side effects include dizziness, insomnia, nausea, and swelling in the ankles or feet. At higher doses, some people experience confusion, hallucinations, or difficulty concentrating. These effects are more likely in older adults and in people with reduced kidney function.
Kidney Function and Dose Adjustments
Amantadine is cleared almost entirely through the kidneys, which means it can build up to potentially toxic levels if your kidneys aren’t working well. Dose reductions are necessary based on how well your kidneys filter. People with moderately reduced kidney function may take 100 mg daily instead of twice daily. Those with severe impairment may only take it every other day or even once a week. Adults 65 and older typically start at lower doses as well, since kidney function naturally declines with age.
If you’re on hemodialysis, the standard approach is 200 mg once every seven days, reflecting how slowly the body clears the drug without full kidney function.