Hello Syndopa is carbidopa + levodopa and is a very potent and efficient drug for the treatment of anterior sclerotic parkinsonism , post-encephalitis , idiopathic disease . Idiopathic reason means unknown reason. Side effects are : Nausea, vomiting, anorexia , orthostatic hypotension, cardiac arrhythmias, PSYCHIATRIC symptoms ( depression with or without suicidal tendency)delirium , hallucinations ( in elderly , as you mentioned that your grand father is taking this drug i.e he is an elderly patient so it is danger and may develop hallucination but not madness ). These are side effects. You didn t mention , why he is taking this drug, so clear this fact. In my opinion consult treating physician and get his opinion. Hope this will help you.