Anti-emetics and anti-nauseants are medications that are used to prevent or reduce nausea and vomiting. They are used to treat a variety of conditions including motion sickness, morning sickness, chemotherapy-induced nausea and vomiting, and postoperative nausea and vomiting. Anti-emetics work by blocking the action of the neurotransmitter serotonin, which is responsible for nausea and vomiting. Anti-nauseants work by blocking the action of the neurotransmitter dopamine, which is responsible for nausea and vomiting. Both types of medications can be used in combination to provide the best possible relief.