# 202 - Summary

# Summary

Schizophrenia and related psychoses
CHAPTER 1
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■Assume that the use of all antipsychotics increases the risk of pneumonia, but especially 
clozapine and high-­dose olanzapine or quetiapine.
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■Concomitant benzodiazepine use should be avoided, where possible.
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■Monitor all patients for signs of chest infection and treat promptly.
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■Offer vaccination against COVID-­19, influenza and pneumococcus to all high-­risk patients.
­dopamine partial agonists) seem to have a lower risk of pneumonia than pure dopamine antagonists.9 Another study found amisulpride (a dopamine antagonist with minimal anticholinergic activity) is not linked to pneumonia.11
Mechanisms
Although studies rarely distinguish between the various forms of pneumonia, cases of 
antipsychotic-­induced aspiration, infective (viral and bacterial) and hypersensitivity 
pneumonia have been documented.16 The mechanism by which antipsychotics increase 
the risk of such pneumonia is not known but is probably multifactorial. Proposed 
mechanisms are outlined in Box 1.2.
An increased risk of pneumonia should probably be assumed for all patients taking 
any antipsychotic (but especially clozapine)21 for any period. All patients should be very 
carefully monitored for signs of chest infection and effective treatment started promptly. 
Consideration should be given to using COVID-­19, influenza and pneumococcal vaccines, although there is no direct evidence to support benefit for pneumonia prevention 
in this specific group of patients. Those patients prescribed clozapine should be proactively monitored and treated for hypersalivation. Pneumonia is likely to increase clozapine levels (see section on clozapine: common adverse effects in this chapter) so close 
monitoring is required. Slower-­than-­usual clozapine titration may prevent cases of 
hypersensitivity pneumonia.14 Extra vigilance is required when re-­exposing to patients 
with history of clozapine-­induced pneumonia who are taking clozapine. With all cases, 
early referral to general medical services should be considered where there is any doubt 
about the severity or type of chest infection.
Summary
Box 1.2  Proposed mechanisms for antipsychotic-­induced pneumonia
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■Sedation
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■Dystonia or dyskinesia
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■Dry mouth
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■General poor physical health
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■Reduced immune response*
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■Clozapine-specific: hypersalivation, constipation
* Clozapine is associated with antibody deficiency and greater use of antibiotics. This increased risk of infection 
is not related to neutrophil counts.20