Some evidence suggests that ginger may help alleviate nausea during chemotherapy, but it was recently shown that it can interact with some chemotherapeutic drugs, which can be dangerous. See the Concerns and Cautions section of the Ginger Supplements & Ales Review.
Ginger and ginger extracts help reduce nausea in certain situations. A recent placebo-controlled study evaluated its effect on people undergoing chemotherapy and the results suggest it may be more useful in some people than in others. For details, see the "What It Does" section of the Ginger Supplements Review, which includes our Top Picks for ginger root powders and extracts.