Can coffee really cause canker sores and if so why?

Canker sores: The precise cause of canker sores remains unclear, though researchers suspect that food sensitivities, particularly to chocolate, coffee, strawberries, eggs, nuts, cheese and highly acidic food may be the cause. You are your best doctor. Try and observe. Maybe make a log of what you eat and that could show if coffee is causing your canker sores.

Not normal: Have never heard of coffee causing canker sores. About 85% of canker sores are caused by the foaming agent ( sodium laurel sulfate) in toothpaste. If you are troubled with canker sores, you might try a toothpaste without this chemical in it. I personally prefer a toothpaste (and mouth rinse) called closys.