[The immune system is affected by psychological factors. High stress levels can change susceptibility to infection and allergy].

The article consists in a review of the evidence of psychological and neural influences on the aetiology and severity of allergy. Histamine release in response to symbolic stimuli and behavioural conditioning of allergy-related immune variables suggest the existence of links via which psychological factors can affect the allergic cascade. Although this has been established in animal species, and is supported by evidence of neuro-immune communication pathways, convincing evidence of its occurrence in humans is sparse. Although asthma and stress symptoms seem to be related, the causal direction of such relationship remains unclear. In view of the occurrence of undocumented allergy and the importance of symptom perception as a basis for optimal medication, the assessment of subjective allergy symptoms is a cogent issue.