Colonic peristalsis during colonoscopy can conceal neoplastic lesions, and antispasmodic agents can cause adverse reactions. Inoue et al. report the benefits of applying the antiperistaltic compound L-menthol to the colonic mucosa prior to colonoscopy. Patients were treated with 1.6% L-menthol or placebo—neither had any adverse effects. The proportion of patients with no peristalsis after treatment and the adenoma detection rate were both significantly higher in the L-menthol group than the placebo group.