Everything you need to know about Itching
Itching refers to an unpleasant sensation that causes the need to scratch –- the medical term for itching is pruritus. Itching may be confined to a certain area of the body (localized), or can be all over the body (generalized). Itching may be associated with a rash, which may either be the cause of the itch or the result of the scratching. For some people, there may be no visible rash associated with their itching. Regardless of the presence or absence of a rash, itching can be debilitating, especially at night when a person is trying to sleep.
Itching and pain are closely-related sensations, since the same nerves transmit both signals to the brain. When the area of skin is scratched, that same area may become even itchier, leading to more scratching. This is called the itch-scratch cycle. In general, itching can be related to a problem with the skin or another underlying disease of the body (systemic disease). When itching is localized to a particular area of skin, a systemic disease usually does not cause it.
What causes Itching?
The causes of itching can be divided into localized and generalized. Areas of itching that are localized on one part of the body are more likely caused by a problem of the skin. The area of the body that itches may give a clue as to the cause of the itch. For example, itching of the scalp is most likely due to seborrheic dermatitis (dandruff), atopic dermatitis, contact dermatitis, psoriasis, or head lice.
Generalized itching may be due to various skin diseases, as well as systemic disease. Skin diseases that cause itching all over the body include hives, atopic dermatitis and contact dermatitis. Itching may also be caused by medications (such as narcotics and other pain medications), infections (such as parasitic infections of the intestines), iron deficiency, liver disease, kidney disease, high or low thyroid function, as well as certain cancers.
As soon as we feel an itch, our first natural response is to scratch the spot of the itch with our fingernails. The reason for this response is simple — we want to remove the irritant as soon as possible. Once you’ve scratched the area of irritation, you are likely to feel some relief. When your brain realizes that you’ve scratched away the irritant, the signal being sent to your brain that you have an itch is interrupted and therefore no longer recognized by the brain.
Even if you don’t remove the irritant, scratching will at least cause pain and divert your attention away from the itching. The irritant that caused the itching is very small, maybe only a few microns in length, so it disturbs only a few nerve endings. When you use your fingernail to scratch the spot where the irritant is, you not only remove the irritant but you irritate a lot more nerve endings than the irritant.