What causes pruritus?

Itching is a kind of self-conspiracy that occurs in the skin and causes scratching. The reason is complicated. The causative factors include internal or external factors, or both.
1. Internal causes of systemic pruritus
(1) visceral disease stomach, intestine, liver, kidney and other organs of functional or organic diseases, especially diabetes, uremia, liver disease patients, often have generalized itching; some tumors such as leukemia, Lymphosarcoma, Hodgkin's disease, mycosis fungoides, and malignant lymphoma patients with skin itching.
(2) neuropsychiatric system disorders cerebral arteriosclerosis, spinal tuberculosis, neurasthenia can also occur systemic or limited local skin itching. Common in the clinical neurosis patients have some illusion that the skin has insects and itchy, and some develop the habit of scratching.

(3) endocrine disorders Some women often have pruritus during pregnancy, usually in the postpartum disappearance, menstrual disorders or ovarian disease often cause female genital itching. Older skin itching may be associated with decreased levels of sex hormones in the body. Thyroid disease patients can have pruritus.
In addition to the above, lesions of infection, drugs, diet (alcohol), food allergy and parasite or fungal infections can cause systemic or limited local itching.
2. External causes can cause generalized or limited localized itching. Changes in temperature often cause skin itching, winter pruritus and summer pruritus patients are extremely sensitive to changes in temperature. Bedding is too hot, suddenly heat or cold may cause itching attack.
Mechanical friction or physical and chemical factors can stimulate the local cause of the itching. For example, some people are sensitive to wool, some alkaline too strong soap, wearing chemical fiber wool and so on.
In addition disinfectants, pesticides, deodorants, dyes and other irritants can make local skin itching.