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“Scratching is one of the sweetest gratifications of nature, and as ready at hand as any.”
– Montaigne
tching, simply stated, is the urge to scratch. The medical term for itching is pruritus. It is a common, everyday experience ranging from a simple, fleeting annoyance (a mosquito bite) to the intense, distressing, unrelieved torment (the itch of scabies) that can result in sleepless nights.
Why do people itch? Let me try to explain. We know that the sensations of pain and itch are carried to the brain by the same nerve fibers, and we know that pain and itching points have similar distribution on the surface of the skin. We also know that it’s possible, by varying the intensity of a stimulus (chemical, electrical, or physical) to cause either pain or itching on a certain portion of the skin.
So, a better way of understanding this complex sensation is thinking of an itch as a sub-threshold pain, or, better still, as a pain that doesn’t hurt. The difference, however, is that an itch occurs only in the skin; pain arises from deeper structures as well. And while itching leads to the urge to scratch, pain leads to withdrawal.
Have you ever bruised, scraped, or skinned your knee or elbow? Have you ever suffered from moderately severe sunburn? If you have, you may remember that at first there were varying degrees of pain. When the bruise, scrape, or burn began to heal, this pain was gradually transformed into an itch – a so-called “healing” itch: a peculiar sensation in the skin that produces a desire to scratch.
Commonly experienced, unpredictable, and poorly understood, itching is the symptom that most frequently prompts a person to visit a dermatologist.
Different people experience, interpret, and tolerate itching in different degrees. One person’s itch might be another person’s tickle; one person’s stinging itch can be another person’s pain. If you have a high itch threshold, a transient mosquito bite or a brush with a poison ivy plant will rarely bother you. Less fortunate people will itch unmercifully at the least provocation, such as a mild allergy to nickel earrings or a simple rash from a leather watchband. No one knows why.
Many years ago scientists thought that the basic cause of itching was the release of a chemical substance called histamine. We now know that itching can be caused by a breakdown of various tissue proteins, and can be precipitated by a variety of stimuli:
What do you do when you itch? You scratch . . . . naturally. Why does scratching relieve itching? Again, no one really knows. It may be that by scratching or rubbing you are substituting the sensation of pain for that of itching. Or, it may be that by scratching or digging with your nails you damage the nerve fibers that cause the itching. Scratching, while it may give you temporary relief, can actually cause more harm than good. It can lead to secondary infection that may require internal antibiotic therapy.
What should you do when you itch? The most important thing to do is determine, if you can, why you began to itch in the first place. If you do not have a clue, and if your itch persists, see a dermatologist. She or he will try to uncover the cause and, if possible, eliminate it.
What you can do to relieve your itching depends, of course, on the cause. No single therapy is effective for all itching. In addition to providing symptomatic relief, most treatments are aimed at eliminating the underlying cause.
For symptomatic relief of mild to moderate itching – regardless of the cause – you can try several over-the-counter remedies:
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