Common side effects
Levodopa works by being converted to dopamine, a chemical messenger that is needed to control the movement through transmission of signals in the brain.
Carbidopa is always given with levodopa. It works by preventing levodopa from being broken down before it reaches the brain. This allows for a lower dose of levodopa, which causes less nausea and vomiting.
Entacapone works by increasing the amount of dopamine, a chemical messenger that is needed to control movements in the brain.