It is recommended not to eat crab after taking cold medicine. Because crabs are aquatic animals and are considered cold in nature. During a cold, it is best to avoid overly cold foods, pay attention to rest, drink more warm fluids, and follow a light, easy-to-digest diet, and to take medicine on schedule. Although eating crab will not cause poisoning, it can decrease the effectiveness of cold medicine, thereby prolonging the duration of the cold. If the cold improves, crabs can be consumed in small amounts.