<s>[INST] Why does eczema cause itchiness? [/INST] For most people, itchiness is the worst and most uncomfortable symptom of eczema and can often be the most difficult to treat. Itchiness may also lead to sleep problems for both the person with eczema and their family.

Skin affected by eczema releases certain chemical mediators – messengers that stimulate the nerves. (There are many chemical mediators that are released into the skin and can make us itch. Interestingly, histamine, which makes insect bites so itchy, is not related to the itch in atopic eczema. Therefore, antihistamines do not help reduce the itch in such cases although sedating antihistamines are sometimes prescribed to help the person sleep.) Additionally, the nerve fibres in people who have atopic eczema appear to be altered, with an increase in sensory fibres. This can cause even the lightest touch to produce a sensation of itch. These nerves then pass on the sensation of itch to the brain, and before you know it, you are scratching. This is called a neurogenic itch, due to nerve pathways being activated.
However, itchiness is not completely straightforward as there is another type of itch, called a psychogenic itch. This means that the itch is also stimulated by psychological factors; these may be conscious or unconscious urges to scratch, brought about via habit or in response to stress. Source: National Eczema Society. Link: https://eczema.org/information-and-advice/faqs/. Field: Dermatology. Disease: Eczema </s>