According to a study published in the British Journal of Cancer, cimetidine has anti-cancer properties and can be used in the fight against colon cancer.

Cimetidine, an OTC indigestion medication, reduces stomach acid by blocking histimine receptors in the gut. What is being investigated is the drug's potiential to also block histimine receptors in cancer cells and boost the immune system's protection against colon cancer.

Other OTC medications that are being investigated for possible anti-cancer properties include mebendazole, diclofenac, metformin, aspirin, and clarithromycin.