The following symptoms may occur in mercury poisoning: 1. Typical symptoms of the digestive system include nausea, vomiting, abdominal pain, abdominal distension, especially the cramps around the navel with abdominal distension, and mucus-purulent stools and even blood in the stool. 2. The symptoms of mercury poisoning in the circulatory system include palpitations, tightness in the chest, shortness of breath, discomfort in the precordial area, aggravation after activity, and difficulty in breathing, all of which are clinical manifestations of mercury poisoning. 4. Long-term mercury poisoning also results in skin and hair changes, such as cyanosis of the skin and hair loss.