Just a few days after the introduction of lithium therapy to treat a 35-year old man suffering from a bipolar disorder, complaints of constipation arose. The issue persisted despite numerous trials with first and second line laxatives at adequate dose and duration over a period of several weeks. After the singular administration of highly dosed macrogol laxatives with electrolytes, a lower dosage was established as maintenance treatment, yielding promising results. However, the potential interactions as well as the possible fluctuations in serum lithium levels when combining a maintenance treatment of both lithium and laxatives remains to be evaluated.