Cimetidine, brand name Tagamet, is a drug commonly used to treat gastroesophageal reflux disease (GERD) as well as peptic ulcers. It blocks one of the histamine receptors known as H2. However, published research in the 1970s involved two cases where tumors regressed following treatment with cimetidine. This spurred additional research into cimetidine’s possible anti-cancer mechanisms.

Cimetidine as an Anti-Cancer Agent

Cimetidine has been shown to have anti-tumor activity in the treatment of colorectal cancer, kidney cancer, and melanoma, among others. Research has uncovered its ability to slow cancer cell proliferation, while also inhibiting cell adhesion. Studies have also found that it helps maintain lymphocyte counts and natural killer (NK) cell counts, both of which are important markers of immune system activity. Finally, cimetidine appears to have an anti-angiogenic property, thus inhibiting cancer cells to form new blood vessels.

Cimetidine can inhibit the action of other drugs, so great care must be taken when considering its use as part of an integrative protocol. However, its off-label use to treat cancer is certainly