Many people have the experience that after eating seafood such as fish and shrimp, they feel itchy skin all over their body, followed by a red mass of varying sizes, called “wind bumps”, which is a common skin allergy phenomenon in life, hives. So what is allergy? What are the causes of skin allergies? What skin diseases can allergies cause? What should we do when skin allergies occur? In fact, allergies are caused by a substance that enters the body and is not compatible with our own immune system, so in order to remove this foreign substance, the body produces a “self-defense reaction”, which gives rise to the phenomenon of allergy. Allergy is divided into two kinds of cases: rapid-onset and delayed-onset, like the one mentioned above, which occurs immediately after contact with the allergen; delayed-onset means that the first contact with the allergen only sensitizes the body, that is, the immune system has a memory of “it”, and the next contact will be a full-blown outbreak. This is the reason why many patients come to the clinic and say that I was fine with the exposure. The main causes of skin allergy are internal and external. Endogenous causes are: the patient’s own allergic constitution, which plays a leading role in the development of skin allergy. External causes include diet, inhalants, UV rays, medications, etc. These substances that can cause allergic reactions are called allergens. Among them, seafood, protein, spicy food, wine, inhalation of pollen, dust mites, cold weather, soap, detergents, etc. are common triggers of skin allergy. Common allergic skin diseases besides the hives we mentioned, there are also eczema, atopic dermatitis, allergic purpura, etc. Symptoms such as erythema, papules, pimples, purpura, exudation, itching, etc. can sometimes even be accompanied by systemic symptoms such as breathing difficulties, abdominal pain, joint pain, fever, etc. So how should we prevent and deal with allergies? First of all, try to avoid contact with allergens, this is especially important for allergic people, if they do not know what allergies can come to the hospital to check the allergens. Furthermore, try not to use hot water to burn or scratch the itchy area. You can take some oral anti-allergy medications, such as loratadine, etc. You can also use some topical creams with anti-itch effect, but it is better to go to the hospital to see a doctor.