There are individual differences in how long it takes for a patient to recover from crab allergy, which is related to the severity of the condition and the measures taken, and cannot be generalized. Crab is a cold, omnivorous protein, and some people may experience different degrees of allergic symptoms after eating it. If the patient’s condition is mild, only localized redness, swelling and itching, then immediately stop eating aquatic products, including fish, shrimp, shellfish, usually within 24 hours can subside on its own. Some people may have generalized itching of the skin with erythema, wind masses and other changes, need to immediately stop eating seafood, while drinking more water to promote excretion, and be anti-allergic, inhibit immune response, detoxification symptomatic treatment, usually takes 4-5 days to subside. During this period, patients should pay attention to a light and easily digestible diet to reduce the burden on the gastrointestinal tract, prohibit the consumption of greasy, spicy and stimulating foods, especially avoid drinking alcohol, and pay attention to abdominal warmth.