When the body is cold, the skin itches and swells when scratched. How's it going?

Suspected scratching is a kind of urticaria.

There are two kinds of skin scratches: one is called simple skin scratches, which are more common in women and belong to physiological abnormal physical reactions. Its symptom is a rash after the skin is scratched by nails or other blunt objects, usually without itching or other uncomfortable feelings.

There is also a kind of dermatoglyphics called symptomatic dermatoglyphics, which is common in young people with allergic constitution. Most of the causes are allergic reactions of skin after external physical stimulation, which make mast cells release histamine bioactive substances, dilate skin capillaries, enhance permeability, and make plasma and tissue fluid penetrate into dermis. People with this kind of skin scratch often feel itchy for no reason, but unlike common urticaria, it will have a rash all over the body. Instead, when scratching the skin with nails or other blunt objects, a series of erythema wheals first appear locally, and then the wheals are edema higher than the skin, and the edge of erythema wheals appears flushed, which is very similar to the traces left by the skin after being whipped by a whip. Some patients with severe symptoms will have swollen lips even if they have been bitten by teeth.

In life, some people often have paroxysmal itching all over their skin, and the itchy parts are not fixed and wandering. When they encounter mental stress or sultry weather, their whole body skin is itchy and burning, but there is no abnormality in their whole body skin at this time, and there is no rash or redness on their skin. What's going on here?

In this case, you can draw a few lines on the flexion side of the forearm with ordinary paper clips and iron wires, and observe the results for about three minutes. After the normal person did the above test, only red stripes appeared on the skin of the tested part, and there were no protrusions. There will be a linear white stripe on the skin of forearm flexor muscle of dermatoglyphic patients, and both sides of the stripe are obviously convex and red, which is called scratch test positive in medicine.

Dermatoglyphics, also known as artificial measles, is an allergic reaction of skin and blood vessels, which is caused by both internal and external causes. There is a special protein in the serum of these patients, which is immunoglobulin IgE. If this protein is combined with allergens, the body will cause a series of reactions. Finally, mast cells around skin blood vessels will release a lot of histamine, which will lead to the expansion of skin blood vessels, and serum will ooze from blood vessels, thus causing itching. This skin scratch test is positive.

The most common allergens causing dermatoglyphics are drugs, especially penicillin and serum preparations, as well as protein from bacteria, fungi and plants and protein from animals.

Many people neglect the treatment of tinea pedis. We should know that the metabolites of various fungi that cause tinea pedis are often regarded as a strong allergen, which will cause antigen-antibody reaction after being absorbed by the human body, and as a result, it will also lead to skin scratches.

To cure skin scratches, of course, we must first eliminate allergens, carry out antibacterial and antifungal treatment, avoid drug allergy and avoid eating fish, shrimp and shellfish. Change your allergic symptoms.

The above premise is to go to the hospital to check whether it is a scratch disease.