I know a prior poster asked, so I wanted to reply. The reason that its believed that ginger works so well is because its chemical structure is very close to a medication called compazine which has been used for a long time for cancer and post operative patients for nausea.....
Most medications that are avalible either over the counter, or as a prescription have a similar herb or natural rememdy. However, never switch from a prescription to an herb without talking to your doctor first.
(glad I paid attention in pharmamcology)