Lithium is the gold standard in the long-term treatment of bipolar disorders and the only substance with a convincing antisuicidal effect in affective disorders. Under regular monitoring, lithium represents mostly a well-tolerated and safe medication. Balancing risk and benefits shows that lithium can also be an off-label therapeutic option during pregnancy and breast feeding. Lithium may exhibit neuroprotective effects and has been linked to a reduced risk of Alzheimer's disease and stroke. In the future, biomarkers of lithium response may be available that enable development of more personalized therapies.