The evidence that ginger helps alleviate chemotherapy-induced nausea and vomiting is inconclusive and it is not recommended for clinical use for this, or for any other type of nausea.Studies have found no clear evidence of harm from taking ginger during pregnancy, though its safety has not been established and it is a suspected risk for mutagenicity.Allergic reactions to ginger generally result in a rash. Although generally recognized as safe, ginger can cause heartburn and other side effects, particularly if taken in powdered form.Unchewed fresh ginger may result in intestinal blockage, and individuals who have had ulcers, inflammatory bowel disease, or blocked intestines may react badly to large quantities of fresh ginger.It can also adversely affect individuals with gallstones and may interfere with the effects of anticoagulants, such as warfarin or aspirin.Ginger, like other dietary supplements, is not effective for treating dysmenorrhea.source:wikipedia