In recent years, with increasing research into antispasmodic agents, topical antispasmodics have attracted considerable attention due to their direct action on the gastrointestinal mucosa and relatively low incidence of adverse reactions. Menthol, a natural terpenoid compound found in peppermint oil, has been confirmed by numerous studies to possess spasmolytic properties. Existing evidence indicates that menthol relaxes intestinal smooth muscle and alleviates spasm symptoms by antagonizing L-type calcium channels on the smooth muscle cell membrane, thereby reducing calcium influx. Furthermore, it exhibits local analgesic effects and can attenuate visceral hypersensitivity. Some studies suggest that oral or topical administration of peppermint oil preparations may improve intestinal spasm during colonoscopy, highlighting its potential utility in digestive endoscopy procedures. Nevertheless, current research on the spasmolytic efficacy and safety of menthol solution when administered via endoscopic irrigation during colonoscopy remains limited, and high-quality clinical trials are urgently needed for validation. This study aims to investigate the effectiveness and safety of menthol solution in relieving intestinal spasm, thereby providing scientific evidence for optimizing colonoscopy procedures.

Inclusion Criteria:

1. Age between 18 and 75 years, regardless of gender;
2. Scheduled to undergo colonoscopy (for screening, diagnostic, or follow-up purposes);
3. Adequate bowel preparation quality (Boston Bowel Preparation Scale score ≥ 6);
4. Voluntarily signed informed consent and able to cooperate with completing study-related assessments.

Exclusion Criteria:

1. Allergy to menthol, cyclodextrin, or related substances;
2. History of severe intestinal diseases (such as ulcerative colitis, Crohn's disease, intestinal perforation, intestinal obstruction, intestinal tumors, etc.);
3. Presence of severe dysfunction of vital organs such as the heart, liver, kidneys, or lungs, or coagulation disorders;
4. Pregnant or lactating women;
5. Use of anticholinergic drugs, calcium channel blockers, or other spasmolytic agents within one week prior to the examination;
6. Psychiatric disorders or cognitive impairment that prevent cooperation with the study;
7. History of contraindications to colonoscopy or serious adverse reactions during previous procedures.