Antiemetics are medications that help treat nausea and vomiting. Common causes of nausea and vomiting are motion sickness, morning sickness in pregnancy, food poisoning, gut infections and labyrinthitis. Nausea and vomiting are very unpleasant symptoms that can be hugely improved with the right choice of antiemetic.
Different antiemetic medicines act in different ways. The different areas of the body that they can act on include the stomach or the brain. Within the brain there are several different receptors that antiemetic drugs can work on. There are even some antiemetics that are useful but we don't fully understand how they work.
If a patient is experiencing nausea and vomiting as a result of side effects of taking other medicines (e.g. strong pain killers or chemotherapy) then antiemetics that work on chemicals in the brain might be the most helpful. However if a patient is experiencing nausea and vomiting due to movement of food through the gut being a bit sluggish (gastrostasis) then some of the antiemetic medicines work to speed up this movement of food may work better. Sometimes more than one antiemetic can be used at the same time if symptoms are severe.