Scratching an itch makes you feel good

After a summer barbecue that stretched on past sunset, I awoke the next morning to find myself covered in itchy mosquito bites.

Some friends told me not to scratch the bites. They say, scratching only makes the itching worse. This is a popular piece of folk wisdom that dermatologists call “the itch-scratch-cycle“.

Sometimes scratching relieves isolated itches, hence the existence of devices such as the back scratcher. Often, however, scratching can intensify itching and even cause further damage to the skin, dubbed the “itch-scratch-itch cycle”.

[emphasis mine]

It is not hard to find this belief reflected on the internet in both reputable and casual sources from a simple Google search: (1) (2) (3). Apparently, many doctors and dermatologists believe it.

However, I’m skeptical. The popular perception that scratching relieves itching has been observed in recent studies. It can’t make it both better and worse? Can it? What’s going on here?

A recent article from the scientific literature sheds some light:

As referred to by the definition of itch sensation, itch is accompanied by the desire to scratch, which in turn reduces the itch. In addition, a hedonic experience (algedonic pleasure188) can accompany the scratching of an itch: “At least it may be noted that scratching an itch with a violence that would cause pain elsewhere may be experienced as one of the most exquisite pleasures”189. The hedonic aspect of scratching can be problematic in chronic itch: patients with atopic dermatitis may report that they scratch until it no longer provokes pleasant sensations rather than until the itch has subsided190. However, albeit being a key factor in the vicious itch/scratch cycle, this clinically important aspect has gained only little scientific attention187, 191

According to the evidence, scratching makes an itch feel better. The itch/scratch cycle is caused by scratching feeling good, not by scratching causing more itching.

I imagine the “scratching makes itching worse” nonsense was spread by parents hoping to frighten children (and doctors hoping to frighten patients) away from excessive scratching. This strategy makes as much sense as telling people with an eating disorder that potato chips will only make them hungrier in the long run. It may cause people to stop overindulging in pleasurable activities, but its dishonest because it’s not the real reason to not overindulge. It’s just bullshit.

If you have a personal policy of never succumbing to hedonistic tendencies and only engaging in activities that produce long-term benefits, then scratching should be avoided. However, for everyone else, scratching can be done in moderation without damaging the skin and is quite pleasurable.

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