Generic Exelon side effects include nausea, vomiting, dizziness, diarrhea, loss of appetite, headaches, abdominal pain (stomach pain), accidental injury, shakiness (tremor), indigestion or heartburn, fatigue, insomnia, confusion, urinary tract infections (UTIs), weakness, constipation, a general ill feeling (known as malaise), drowsiness, gas runny or stuffy nose, increased sweating, upper abdominal pain, flu-like symptoms (such as a fever and chills), a worsening of Parkinson's disease symptoms (in people taking the drug for Parkinson's dementia), weight loss dehydration, belching. More serious side effects include severe nausea, vomiting, diarrhea, or weight loss depression, anxiety, hallucinations, aggressiveness, high blood pressure (hypertension), fainting, a dangerously slow heart rate (bradycardia), stomach ulcers or intestinal ulcers, difficulty passing urine, seizures and worsening of asthma.