Rats! You beat me to it.
This is one list I found for lithium's side effects:
tremor, diarrhea, vomiting, drowsiness, muscle weakness, anorexia, nausea, blurred vision, dry mouth, fatigue, increased white blood cell count.
But not to worry. If it prevents Alzeimer's the patient (victim?) will remember to take their big pharm medicine script for each of the side effects.
Interestingly, it's used for bipolar and some other mental disorders. So everyone taking it to treat their bipolar disorder is subject to all these side effects? Wow.