Glasgow Antipsychotic Side-effect Scale

Glasgow Antipsychotic Side-effect ScaleThe Glasgow Antipsychotic Side-effect Scale (GASS) is an easy to use self-reporting questionnaire aimed at identifying the side effects of antipsychotic medication. It consists of 22 questions with points assigned based on answers given by the patient.


GASS was developed in 2007 after taking into account some of the strengths and weaknesses of other scales in use at the time. Important anti-psychotic side-effects were listed and ranked in importance of medical consequences and patient acceptability. 22 questions were devised to summarise the prioritised side effects, with priority given to long-term adverse medical consequences.

The questionnaire was validated against the Liverpool University Neuroleptic Side Effect Rating Scale (LUNSERS) using the completed results from 50 outpatients.[1]

The questionnaire should only take 1-2 minutes to complete. It is good clinical practice to give this questionnaire to patients before outpatient appointments as a means to regularly review side effects.

The great benefit of it is that it identifies what specific problems the patient is suffering from. Depending on the score, you are able to establish if the patient is suffering from side effects of antipsychotics.


1. Waddell L. and Taylor M. (2008) A new self-rating scale for detecting atypical or second-generation antipsychotic side effects. Journal of Psychopharmacology 2008; 22(3): 238-243.