Will you die from swallowing hydrogen peroxide?

It depends how much: A small amount will not likely hurt you. Sometimes people will gargle with hydrogen peroxide to cleanse the mouth. This is not recommended. A little bit of the solution may be swallowed and should not give you a problem. If you are drinking the liquid, you are likely to have problems.

What concentration?: Per the National Capital Poison Center: consumption of concentrated hydrogen peroxide (H2O2) has lead to deaths. http://www.poison.org/poisonpost/june2012/hydrogenperoxide.htm). Ingestion of concentrated H2O2 can lead to venous or arterial gas embolism, distention of hollow viscus with rupture, & respiratory tract obstruction/ pulmonary aspiration. Laryngospasm, coma, convulsions, confusion, >