Yes, there is a big adjustment when you are on any dosage but especially when higher up. Did his doctor just cut out 800 mg in one day?

If so, you need to watch your dad closely for something called Neuroleptic Malignant Syndrome - key symptoms are high fever and all over rigidity. This happens to some people who are taken off their PD drugs too abruptly, and reducing his dosage in half is too much too soon.

You can expect what doctors call symptom rebound - a withdrawal effect where his symptoms will be much more intense and uncomfortable. I went through this and it lasted a good month; I also had new symptoms temporarily appear. It is alarming to hear of doctors doing this; with neurologists there is no excuse.

Long ago in PD Land, doctors used to put patients on "drug holidays" and when they noted patients actually dying from it they ended the practice. Any patient should be slowly tapered down over the course of weeks if not longer. Our brains become dependent on the dopamine boost and to suddenly take a good portion of it away is not so good- just common sense. The brain and body need time to adjust accordingly.

Don't mean to alarm but just want you to look out for him, as most doctors won't. If he gradually worsens over days; that is more like a symptom rebound. He will probably his his baseline and be okay but if you do note any sudden rigidity, unexplained fever, it is serious.

Here is a good overview; it is not uncommon that doctors bring this on.

Infections, drug changes can bring Parkinson's to the ED. (ER)

Hope he "normalizes" and finds relief soon.

Laura