Several drugs, several infections and several poisons can cause parkinsonism. A few drugs used to treat blood pressure, vomiting, mental disorders and seizures can cause or worsen parkinsonism. If they are the cause of the problem, ending them will end the problem, although it may take weeks or months for the signs and symptoms to go away. If they are making Parkinson's disease worse, they need to be stopped, but the disease won't go away.
Many brain infections can leave a patient with parkinsonism.
A brain infection is called encephalitis . Encephalitis is always serious but fortunately rare. The influenza epidemic during the early part of this century caused a number of cases of encephalitis and resulting parkinsonism. The latter two have interesting stories to tell. The cycad nut grows on Guam, where natives often make a tea of it.