Ondansetron

Ondansetron, formerly sold under the brand-name Zofran, is an antiemetic usually used to treat the nausea associated with chemotherapy, radiation therapy, and surgery. It works by blocking receptors to a certain type of serotonin.
It can cause headaches, dizziness, and constipation, but serious side effects are rare.
Ondansetron at Wikipedia
Category:Pharmaceuticals