Approximately 40% of bipolar patients experience rapid cycling, and half of these suffer from ultra-rapid or ultradian cycling. These patterns are also common in children. Rapid-cycling bipolar disorder is difficult to bring to remission and often requires treatment with four or more classes of psychotropic medications. Lithium, even in combination with anticonvulsants or antidepressants, is often associated with residual episodic depressions. Concerns with adjunctive antidepressant treatment include their low response and remission rates and their tendency to cause switch into mania. Atypical antipsychotics and selected agents within the anticonvulsant class are becoming increasingly important in the treatment of rapid cycling. In the absence of clear treatment guidelines, the use and sequencing of drugs in complex combination treatment remains exploratory, but should be individualized based on careful prospective mood charting by the patient. Use of several drugs below their side-effect thresholds may prevent certain side effects. In children, long-term safety considerations are particularly important in the absence of a strong controlled clinical trials database.