What Are the Most Common Causes of Leg Rashes?

Itching is a dermatological symptom with only itching of the skin without primary skin damage. According to the scope and location of skin itching, it is generally divided into two categories: systemic and local.

Basic Information

English name: pruritus
Visiting department: dermatology

Common causes: Environmental factors, topical medications, certain irritation, primary diseases, etc.
Common symptoms: Paroxysmal pruritus, heavy at night, with scratches, blood clots, pigments, etc.

Causes of pruritus

1. Systemic pruritus is often the accompanying or first symptom of many systemic diseases, such as uremia, biliary cirrhosis, hyperthyroidism or hypothyroidism, diabetes, malignant tumors, and neuropsychiatric pruritus. The external causes of systemic pruritus are related to environmental factors (including humidity, season, biological or chemical stimuli in the working environment), topical drugs, soaps with strong alkaline, and sebaceous and sweat glands in patients' skin, resulting in dry skin. .

2. The cause of local pruritus is sometimes the same as general pruritus, such as diabetes. Anal pruritus is mostly related to ascariasis, hemorrhoids, and anal fistula. Vulvar pruritus is often associated with leucorrhea, vaginal trichomoniasis, vaginal fungal disease, gonorrhea, and cervical cancer. Scrotal pruritus is often associated with high local skin temperature, sweating, friction, and fungal infections. The occurrence of pruritus is mainly caused by the release of chemical mediators such as histamine, substance P, kinin, and protease.

Clinical manifestations of pruritus

Systemic pruritus

More common in adults, itching often starts from one place and gradually spreads throughout the body. It is often paroxysmal, especially at night. In severe cases, itching is persistent with paroxysmal aggravation, drinking, coffee, tea, mood changes, spicy diet stimulation, mechanical scratching, warm bedding, and even some hints. Can promote the onset and aggravation of itching. Frequent scratches, hemorrhoids, hyperpigmentation, and even eczema-like changes, lichen-like changes, pus dermatosis, and lymphangitis and lymphadenitis.

(1) Senile pruritus occurs frequently in the elderly, often with the most itchy trunk, mostly due to factors such as reduced sebaceous gland function and dry skin. Female patients may be a manifestation of postmenopausal syndrome.

(2) Winter pruritus is more common in adults, and children can also develop it. It often occurs when the temperature changes sharply in the late autumn and winter. Patients often start to itch when entering the warm room or undressing before going to bed.

(3) Summer pruritus often causes dampness and heat to induce itching, and increased sweat in summer can make itching worse.

2. local pruritus

(1) Anal pruritus is more common in middle-aged men, and children with ascariasis can also develop it. Itching is generally limited to the anus and surrounding skin, and can sometimes spread to the perineum, vulva and scrotum. Because often scratching is only anal skin hypertrophy, can also show secondary damage such as mossy or eczema.

(2) Scrotal pruritus Pruritus is mainly confined to the scrotum, and can sometimes involve the penis, perineum, and anus. Due to constant scratching, mossy-like changes, eczema-like changes, and secondary infections are caused.

(3) Pruritus pruritus Itching often occurs on the labia majora and labia minora. Due to constant scratching, the labia often has skin hypertrophy and maceration, and the clitoris and vaginal mucosa may have redness and swelling.

Pruritus Diagnosis

It can be diagnosed based on itching at first onset and without primary skin lesions. In order to find the cause, a detailed medical history should be asked, and a comprehensive physical examination and necessary laboratory tests should be performed.

Differential diagnosis of pruritus

This disease needs to be distinguished from eczema, worm dermatitis, lice, scabies, atopic dermatitis, neurodermatitis, and nodular prurigo.

Pruritus Treatment

Finding the cause and avoiding the inducing factors is the key to prevention and treatment. Avoid scratching, rubbing and scalding with hot water to relieve itching. Life should be regular and you should wear soft clothes and avoid bathing. Avoid alcohol, strong tea, and spicy foods such as chili, pepper, and mustard. Patients who are nervous and emotionally disturbed should pay attention to rest and appropriately change the bad living environment.

Topical treatment

(1) Low pH cleaners and lubricants.

(2) Coolants and local anesthetics include menthol, camphor, carbolic acid, enna (EMLA), a mixture of local anesthetics lidocaine and prilocaine.

(3) Topical antihistamines and topical glucocorticoids.

(4) Immunosuppressive agents.

(5) Strontium salt.

2. Systemic treatment

(1) Antihistamines, calcium, vitamin C, sodium thiosulfate, and sedative hypnotic drugs can be used according to the condition.

(2) Systemic pruritus can be blocked with procaine hydrochloride veins.

(3) Thalidomide (response stopped) to treat inflammatory skin diseases.

(4) Naloxone, an opioid receptor antagonist, is effective in treating bile pruritus and uremia pruritus.

(5) Ondansetron serotonin receptor antagonist