Exelon (rivastigmine) improves the function of nerve cells in the brain. It works by preventing the breakdown of a chemical that is important for the processes of memory, thinking, and reasoning. People with dementia usually have lower levels of this chemical. Exelon is used to treat mild to moderate dementia caused by Alzheimer's or Parkinson's disease. Exelon is not a cure for Alzheimer's or Parkinson's disease.