How do I overcome severe nausea caused by anxiety when I get so lightheaded I can't think straight?

Cutting to the chase. - ginger will help the nausea. But, it is important to work on the primary issue which is you anxiety. Please start with a comprehensive medical evaluation. There a # of ways to address anxiety: cognitive behavioral therapy, behavior modification, individual psychotherapy, group psychotherapy, psychotropic medications, qi gong, tai chi, acupuncture, acupressure, homeopathy, meditation ; yoga.