Hello
The centre in the brain responsible for vomitting is called the Chemoreceptor trigger zone in short CTZ.This is the area when stimulated can cause vomiting.There are several drugs which acts on this center like , ondansteron and granisetron and inhibits vomiting .But does not acts in case of motion sickness.
But no body can assure you 100% safety against vomiting even after taking these drugs but will definitely help.
I hope this helps you.
Regards.
Dr.Tharun
__________________
If I answered your question please clickACCEPT.POSITIVE FEEDBACK or BONUS is very much appreciated

