Amantadine (Symmetrel) is a medication that has U.S. Food and Drug Administration (FDA) approval for use both as an antiviral and an antiparkinsonian medication. However, it is not an effective antiviral drug and is no longer used for this indication. However, it is used for several “off label”, that is not FDA-approved indications, including fatigue of multiple sclerosis and migraines.
Amantadine has a blocking effect on the NMDA receptor, which is involved in pain messaging in the brain. Other NMDA receptor blockers are an Alzheimer’s drug memantine (Namenda) and magnesium. There are only two case reports – one of 14 patients (10 responded to amantadine) and another report of 3 patients with migraines responding to amantadine. So, this is one of the drugs we try after the failure of many other drugs.
Amantadine does have the advantage of having few side effects, but its efficacy in migraines is purely anecdotal.
