Akathisia: Onset and Duration

Akathisia often appears after starting a causative medicine or increasing exposure, although other patterns occur. It may persist, emerge after changes in treatment or be difficult to distinguish from longstanding restlessness. The timing relative to dose changes and interacting medicines is therefore important.

Akathisia is a movement-related adverse effect characterised by distressing inner restlessness and often a need to move. Antipsychotics and some other medicines can cause it. It is not simply ordinary anxiety or voluntary fidgeting, and the subjective discomfort can be severe even when visible movement appears relatively mild to an observer.

A symptom diary can support clinical assessment by recording onset, severity, sleep and treatment changes. However, timing alone does not prove the cause, and other explanations must be considered. Some medicines remain in the body for a long time, so improvement after adjustment may not be immediate. Duration and treatment history also influence terminology used by specialists. The person should not be expected simply to tolerate severe symptoms while waiting indefinitely. Early review can clarify the likely mechanism and identify a management plan suited to the medication, physical health and underlying psychiatric needs.

The chronology should include changes in interacting medicines as well as the antipsychotic prescription. Exposure can rise without an obvious change in the labelled dose. Long-lasting drugs can also produce delayed changes. A complete timeline helps the prescriber assess causation and plan review, while avoiding the assumption that a stable prescription excludes a newly emerging medication-related adverse effect.

Further reading: DailyMed prescribing information (1); DailyMed prescribing information (2); Research record 2877708.