The following symptoms will occur after eating crabs depending on the situation: 1. If the poisoning is caused by eating crabs that are not fresh, the patient will have mainly gastrointestinal symptoms, the patient will have nausea, vomiting, headache, dizziness, abdominal pain, diarrhea and other uncomfortable symptoms, the patient will not want to eat, weakness and a series of symptoms, which should be promptly sent to the hospital for infusion treatment. 2. The patient will have a rash, itching all over the body, facial swelling, and even breathing difficulties, asthma and other symptoms, which can seriously endanger the patient’s life due to respiratory failure. 3, the patient may also have a fever, coma, shock, etc.