The fear of heat and cold is a clinical manifestation of increased metabolism caused by excess thyroxine. The immune system and metabolic function of the elderly are decreasing, so they are prone to hyperthyroidism (hyperthyroidism), which causes the symptoms of being cold and afraid of heat. Prevention: 1. In terms of diet, we should pay attention to the absorption of iodine, so we should eat more iodine-rich foods such as kelp and seaweed, and we should eat a balanced diet and not eat too spicy and stimulating foods to avoid stimulating the thyroid gland and causing hyperthyroidism in the elderly. 2, to pay attention to personal and environmental hygiene, to prevent infection to the virus, because many diseases can cause hyperthyroidism in the elderly, such as respiratory infections may lead to hyperthyroidism in the elderly, 3, to improve physical fitness, often physical exercise, but should be measured, because of the limited exercise ability of the elderly, so we should carefully choose the type of exercise, playing Tai Chi The elderly should choose the type of exercise carefully, such as playing Tai Chi, jogging, are good choices.