Dizziness after eating crayfish may be an allergic reaction, some people may be allergic to the application of seafood, crayfish belongs to a seafood. Allergic reaction is an antigenic antibody reaction, the patient can appear fever, headache, dizziness, but also a generalized rash, in serious cases may appear palpitations, chest tightness, shortness of breath, and may even be life-threatening. If an allergic reaction occurs, it is important to stop eating in time and apply some anti-allergy medication if necessary, such as cetirizine or Xithromax, oral vitamin C, intramuscular diphenhydramine if necessary, or corticosteroids in severe cases.