Amantadine (Symmetrel)

Amantadine is an antiviral medicine with modest anti- Parkinsonian effects. Its mechanism of action is uncertain and it is mainly used to decrease dyskinesia in people with advanced Parkinson's. It can also be prescribed to help combat fatigue because of its weak stimulant effect.

Amantadine is usually taken twice daily and can cause side effects of confusion and hallucinations. As it can also cause insomnia, the second dose should be taken several hours before going to bed.

Antimuscarinics

Antimuscarinics are generally not used for idiopathic Parkinson's as they are not as effective as dopaminergic medicines and can cause confusion and cognitive impairment. They may be useful in younger people with tremordominant Parkinson's, but careful monitoring is required.