In general, it is not recommended to consume crab and watermelon at the same time because both crab and watermelon are cold foods, and consuming them in large quantities at the same time may cause adverse stimulation to the gastrointestinal tract. In particular, people with gastrointestinal dysfunction themselves may experience abdominal pain, bloating, diarrhea and other gastrointestinal reactions, so it is recommended to adjust the consumption time of both appropriately, with an interval of about 2-3 hours. If people with slight allergy to seafood, the allergy symptoms may not be obvious after consuming crab. However, if consumed at the same time with watermelon, it may cause or aggravate allergic reactions, and some people may experience obvious redness, edema, rash at the skin, or even general allergic symptoms such as fever, vomiting, dizziness, and weakness. In addition, the simultaneous consumption of the two may also reduce the absorption rate of nutrients, thus reducing the nutritional value. Therefore, it is recommended that after consuming watermelon or crab, wait until a period of time between food digestion before consuming the other, in order to avoid causing adverse reactions in the consuming population and to improve the absorption of nutrients.