The extended release amantadine formulation is commonly used to treat dyskinesias in people receiving levodopa therapy for Parkinsons disease. A 2003 Cochrane review had concluded there was insufficient evidence to prove the safety or efficacy of amantadine to treat dyskinesia.In 2008, the World Health Organization reported amantadine is not effective as a stand-alone parkinsonian therapy, but recommended it could be used in combination therapy with levodopa. Influenza A
Amantadine is not recommended for treatment or prophylaxis of influenza A in the United States. Amantadine has no effect preventing or treating influenza B infections. The US Centers for Disease Control and Prevention found 100% of seasonal H3N2 and 2009 pandemic flu samples were resistant to adamantanes (amantadine and rimantadine) during the 2008–2009 flu season.The U.S. Centers for Disease Control and Prevention (CDC) guidelines recommend only neuraminidase inhibitors for influenza treatment and prophylaxis. The CDC recommends against amantadine and rimantadine to treat influenza A infections.Similarly, the 2011 World Health Organization (WHO) virology report showed all tested H1N1 influenza A viruses were resistant to amantadine. WHO guidelines recommend against use of M2 inhibitors for influenza A. The continued high rate of resistance observed in laboratory testing of influenza A has reduced the priority of M2 resistance testing.A 2014 Cochrane review did not find evidence for efficacy or safety of amantadine used for the prevention or treatment of influenza A.

Extra-pyramidal side effects
An extended release formulation is used to treat levodopa-induced dyskinesia in patients with Parkinsons disease.
There are also reports of significantly improved consciousness in patients treated for non-traumatic cases of DoC, such as in the case of a subarachnoid hemorrhage, cerebral hemorrhage, and hypoxic encephalopathy. In 2018 the American Academy of Neurology (AAN) updated treatment guidelines on the use of amantadine for patients with prolonged DoC, recommending the use of amantadine (100–200 mg bid) for adults with DoC 4–16 weeks post injury to support early functional recovery and reduce disability. Neuroplasticity and overall functional recovery in patients with brain injury
In various studies, amantadine and memantine have been shown to accelerate the rate of recovery from a brain injury. The time-limited window following a brain injury is characterized by neuroplasticity, or the capacity of neurons in the brain to adapt and compensate after injury. Thus, physiatrists will often start patients on amantadine as soon as impairments are recognized. There are also case reports showing improved functional recovery with amantadine treatment occurring years after the initial brain injury. There is insufficient evidence to determine if the functional gains are a result of effects through the dopamine or norepinephrine pathways. Some patients may benefit from direct dopamine stimulation with amantadine, while others may benefit more from other stimulants that act more on the norepinephrine pathway, such as methylphenidate. It is unclear if treatment with amantadine improves long-term outcomes or simply accelerates recovery. Nonetheless, amantadine-induced acceleration of recovery reduces the burden of disability, lessens health care costs, and minimizes psychosocial stressors in patients. Adverse effects
Amantadine is generally well tolerated and has a mild side-effect profile.