Treating Multiple Chemical Sensitivity as a Specific Phobia using Cognitive Behavioural Therapy: A Case Study in an Older Adult

Multiple Chemical Sensitivity (MCS) is a poorly understood condition characterised by physical symptoms triggered by minimal exposure to odorous or chemical agents, often without identifiable organic pathology. This case study describes the treatment of MCS in an older adult referred to the respiratory team who had developed persistent, generalised reactions to odorous stimuli following an acute toxic inhalation. These symptoms led to severe avoidance, functional impairment, and suicidal ideation. After no organic pathology was identified, the patient was referred for psychological assessment. Diagnostic assessment identified symptoms that were not consistent with other psychological disorders and led to a formulation instead underpinned by understanding the problem as a specific phobia. Treatment spanned 14 sessions, beginning with virtual delivery due to avoidance, progressing to in-vivo exposures, and concluding with relapse-prevention planning. Outcome measures indicated substantial reductions in anxiety and health-related worry, with all functional goals achieved. Gains were maintained at 10-month and 22-month follow-up, with remission of anxiety and large reduction in belief ratings for previously feared stimuli. This case highlights the possibility that some MCS presentations can be understood and treated as a type of specific phobia and supports the input of clinical psychologists in respiratory teams. This adds to the evidence base suggesting that there is a key psychological underpinning to the syndrome, and that CBT can support recovery.