Itching

Itching (Pruritus): Elusive and Exhausting Symptom

Itching, or pruritus, is an unpleasant sensation on the skin that triggers an irresistible urge to scratch it. It is one of the most common symptoms in dermatology and general medicine. Itching can be acute and short‑lasting (e.g., from a mosquito bite) or chronic and exhausting, significantly reducing quality of life by disrupting sleep and causing psychological discomfort. It is important to understand that itching is not merely “irritation,” but a complex process involving the nervous system.

How Does the Sensation of Itching Arise?

It was previously thought that itching was merely a mild form of pain. Today it is known to be an independent sensation transmitted via specific nerve fibers from the skin to the brain. These nerve endings can be activated by various chemical mediators, the primary one being histamine. It is released from mast cells during allergic reactions and causes itching in hives or insect bites. However, other mediators exist, so not all itching is relieved by antihistamines.

Causes of Itching: From Dry Skin to Systemic Diseases

The causes of itching can be very diverse:

• Skin diseases (most common cause):
  • Dry skin (xerosis): Especially common in older adults and during winter.
  • Atopic dermatitis (eczema), psoriasis, seborrheic dermatitis, pediculosis.
• Systemic diseases: Sometimes itching without an obvious rash can be the first symptom of an internal illness.
  • Liver diseases: In cholestasis (bile stagnation) bile acids accumulate in the blood, irritating nerve endings. Example — itching in pregnancy.
  • Chronic kidney failure.
  • Thyroid gland disorders.
  • Some oncological diseases (e.g., lymphomas).
• Neurological and psychogenic causes.