Inhaled chili pepper substance shows therapeutic potential in refractory chronic cough

Repeated exposure to aerosolized capsaicin paired with cough suppression helps reduce symptoms in patients with refractory chronic cough (RCC), a small study has found.

A total of 14 adult patients with RCC were randomized to undergo behavioural cough suppression therapy (BCST) in combination with either six treatment sessions involving exposure to nebulized capsaicin in progressively larger concentrations while actively suppressing cough (n=8) or six sessions of exposure to a single subthreshold dose of capsaicin (sham; n=6).

Researchers assessed the efficacy of treatment using the Leicester Cough Questionnaire (LCQ; primary outcome). They also conducted urge-to-cough (UTC) testing to measure both UTC and cough frequency, which served as secondary outcome measures.

While the results on all measures were more favourable in the intervention than in the sham group, the difference in treatment effect on cough frequency was evident only during UTC testing.

At week 3 after treatment, LCQ changed by a mean of 2.95 in the intervention group as opposed to 1.75 in the sham group (p=0.23). Cough frequency during UTC testing decreased by 97 percent and 56 percent, respectively (p<0.0001).

Within-group comparisons revealed strong evidence of change in LCQ the treatment group (p<0.001) and moderate evidence of a change in the sham group (p=0.08).

Despite the very small sample size, the study provides proof-of-concept evidence to support further investigation of repeated exposure to nebulized capsaicin paired with BCST in the treatment of RCC.