Antispasmodic drugs are cheap, effective and generally safe. They may improve outcomes in colonoscopy, however their use has not been consistent or widespread. This manuscript reviews the three most commonly used antispasmodics in colonoscopy, namely, hyoscine butylbromide (and related ammonium compounds), glucagon and peppermint oil. The pharmacology, action and safety of the agents, as well as the evidence for them improving colonoscopic outcomes will be discussed. In addition to polyp detection, other colonoscopic outcome endpoints of interest include cecal and ileal intubation, and patient comfort. The drugs studied were all found to be effective gastrointestinal antispasmodics with good safety profiles. There is insufficient evidence to conclude whether antispasmodics improve cecal intubation rate, predominantly because the baseline rates are already high. Antispasmodics probably have efficacy in reducing cecal intubation time especially in those with marked colonic spasm. Antispasmodics do not offer significant benefit in polyp detection or improving patient comfort during colonoscopy. Future studies should focus on inexperienced colonoscopists as well as those with marked colonic spasm, in whom the greatest benefit seems to lie.