If the body is feeling sick it is generally an indication that the individual has taken something in that it needs to throw out, or it is busily processing a toxin and does not need anything else going in to detract from that biochemical process. Once the cause has been established, it is better to use homeopathic medication to encourage a cure rather than a drug that stops the sensation of nausea.
In cases where nausea is part of a treatment course, such as anticancer drugs or radiation, antiemetics are essential to allow the appetite to be maintained. Not eating during serious illness will not allow the body to repair as well as it should. The use of antiemetics is also permissible if it is for short-term use such as travel sickness.