Pruritus is the most common symptom in patients with skin diseases. Allergic skin diseases, such as eczema, urticaria, contact dermatitis, papular urticaria, and drug allergy, are often accompanied by itching. So, is itchy skin always an allergy?
Not necessarily, the cause of itchy skin is more complex, suffering from liver and gallbladder disease, renal insufficiency, diabetes, thyroid disease and other visceral diseases, and even some malignant tumors, may appear itchy skin; eating certain foods, taking certain drugs, contact with certain soaps, dyes, clothing, feathers and other substances, or by mosquito bites, or by the influence of dry climate environment, may also cause itchy skin. Therefore, when itching of the skin occurs, a comprehensive analysis should be made to find the cause and make a clear diagnosis to avoid misdiagnosis and mistreatment.
What are the common diseases associated with itching? We are divided into three parts to understand the diseases that can cause itching.
I. Allergic skin diseases with itching
Eczema
Eczema is one of the most common diseases in dermatology and is an inflammation of the skin caused by a variety of internal and external factors. It is related to allergy and has a complex etiology. Clinically, itching is pronounced, with small red rashes and blisters in the acute phase, which may have yellow exudate; the chronic phase is often dominated by skin hypertrophy and is prone to recurrent episodes. However, care should be taken to differentiate it from other skin diseases, especially ringworm and ringworm, and fungal examination can be performed; ringworm can be detected as a fungus, while eczema cannot be detected as a fungus. In addition, eczema should be actively searched for causes and possible triggering factors should be removed in order to avoid recurrence.
Contact dermatitis
Contact dermatitis is an inflammation of the skin caused by contact with external substances. It is characterized clinically by sharp-edged damage at the site of contact, ranging from edematous erythema in mild cases to papules, blisters, and even blisters in more severe cases, and can cause skin necrosis in more severe cases. There are many substances that can cause contact dermatitis, which can be classified as animal, vegetable and chemical by their nature. The common ones are metals, plastics, rubber, fragrances, etc. Allergen testing can be done to avoid contact, and with proper treatment, it can be easily cured.
Urticaria
Urticaria is commonly known as wind-dam, wind bumps. It is characterized by limited, temporary, pruritic flushing of the skin and wind clumps. It often occurs suddenly, in batches, and then fades rapidly after a few hours, leaving no trace after fading, but can recur. The cause of urticaria is complex and the allergens are widespread. Chronic urticaria can be tested for allergens if necessary, and for allergens that cannot be avoided, desensitization or preventive medication can be administered.
Papular urticaria
Most of them are caused by insect bites. It often develops in the spring and autumn, mainly in children and adolescents. It presents as a papule with a fusiform shape and a central blister. There is intense itching. The rash usually resolves in 1 to 2 weeks, but the cause of the disease is not removed and is prone to recurrence. However, as the disease increases in age or frequency, it may gradually resolve until it is no longer present.
Drug rash
Drug rash, also known as drug dermatitis, is an inflammation of the skin and mucous membranes caused by drugs that enter the body through oral, topical, and injectable routes. Almost all drugs have the potential to cause dermatitis, and some people think that Chinese medicine is safe, but in fact, Chinese medicine can also cause drug rash. Drug rash is mainly manifested as skin and mucous membrane damage in mild cases, but can be life-threatening in severe cases. Severe drug rash has a high mortality rate and should be resuscitated early. Patients who have suffered from drug rash should keep a record of allergic drugs under the guidance of their doctors and avoid using similar drugs in the future so as to eliminate the recurrence of drug rash.
Second, non-allergic skin diseases with pruritus
Pruritus senileis
The most common, in winter, many elderly people undress at night when the bed, the skin will itch, and the more scratching, the more itchy scratching, until scratched, to slightly stop itching, sleep. This is pruritus in the elderly. Pruritus in the elderly population in China, the prevalence rate of more than 10%. This is because the elderly are generally skin atrophy, thinning, less sweat, dry, and lack of sebum lubrication, so that the nerve endings within the skin more easily stimulated by changes in the surrounding environment hot and cold, inducing itching. Pruritus in the elderly is generally generalized pruritus, mostly in the limbs and trunk, especially the lower extremities, especially the front of the calf is heavy.
Pruritus in the elderly, but also with some habits, such as the love of hot water bathing, bathing too often, the use of alkaline soap or medicinal soap, so that the already dry skin lost the sebum moisturizing. Therefore, the elderly should not take too many baths; water temperature should be kept at about 50 ℃; do not use alkaline soap or soap, you should choose a neutral bath soap or body wash; if the skin is dry, you should use emollient cream.
Clothing for skin protection is also important. First of all, wear cotton clothes, especially underwear, do not wear clothes made of chemical fiber materials, because chemical fiber materials tend to cause static electricity and itching; secondly, clothes should be worn loosely, do not tighten on the body. Many elderly people are afraid to eat high-fat food in terms of diet. In fact, this is not good for health. Fat generates heat to help people withstand the cold and moisturizes the skin. Moderate intake of high-fat foods can prevent pruritus in the elderly. Fatty foods are also good for the intake of vitamin A and vitamin E, which have a role in combating dry and aging skin.
Pruritus during pregnancy
Itchy skin during pregnancy is not necessarily a result of skin allergies, but high bile acids in the body can also trigger intense itching. Therefore, if you have itchy skin during pregnancy, do not simply think it is a skin allergy, but go to the hospital for a blood test to determine if it is “intrahepatic cholestasis during pregnancy”. You should not scratch or apply medication, as this may cause adverse consequences. In the absence of any treatment, the itching caused by cholestasis during pregnancy usually lasts until delivery, and in severe cases it can affect the health of the fetus, so it is important to cooperate with the doctor for active treatment.
Scabies
Scabies, also known as “dry sores”, is a chronic itchy skin disease caused by scabies parasites on the surface of human skin. Scabies easily invades tender parts of the skin, such as finger crevices, the abdomen, and the inner thighs. Small red rashes and blisters may appear in these areas, and in men, hard nodules appear in the scrotum and penis area with intense itching.
Scabies is transmitted by two ways: direct infection: direct contact with scabies patients is transmitted, which is an important way of scabies transmission. Indirect infection: contact with the clothing and bedding of the scabies patient, etc. Once scabies is diagnosed, treatment is relatively easy and can be treated externally with sulfur ointment or lindane ointment, but it should be noted that patients in the family or group dormitory should be treated at the same time.
Tinea corporis, tinea corporis and tinea pedis
Tinea corporis, tinea cruris and tinea pedis are skin diseases caused by fungi. Tinea corporis and tinea cruris are often ring-shaped with small red rashes, small blisters and flaking around the edges. A fungal test can clarify the diagnosis.