For most patients lithium has some kind of adverse effect, the severity of which usually depends on lithium concentration in the blood. As the lithium levels increase, so does the severity of the adverse effects. The smaller the doses, the less severe the adverse reactions. Lithium overdose may manifest itself in the following symptoms:
dizziness
sickness
poor coordination
tiredness, sleepiness
thirst
frequent urination
rash, pimples
muscle spasms