If the diagnosis of catatonia is uncertain, the lorazepam challenge can help distinguish.

Assess for features of catatonia at baseline, ideally using a scoring system such as the [[Bush-Francis Catatonia Rating Scale]].

Administer 1-2mg lorazepam by the intravenous, intramuscular or oral route.

Re-assess after 5 minutes (intravenous), 15 minutes (intramuscular) or 30 minutes (oral). A 50% improvement suggests that catatonia is likely and that there is likely to be a good response to further treatment with benzodiazepines.

If there is limited response, repeat the test with one further dose of lorazepam.

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