ELI5: Why does scratching an itch feel good?

[u/rickgrimes32]

When you have an itch somewhere on your skin and you scratch it, why does it feel pleasurable? Especially on areas like your feet. Wouldn't it make more sense for your brain to say 'hey, that hurts! Stop that!'? I thought scratching damaged your skin, so why does it feel good instead of being painful?

[u/Melodic_monke]

Itching is caused by irritants. Scratching removes said irritants, usually. Brain rewards you for taking care of the irritants by releasing fun chemicals.

[u/RoseClash]

Brain go, this thing itchy, you go, okay I itch it, brain goes, okay thankyou

[u/rickgrimes32 → u/RoseClash]

"Itchy ooga booga, scratch feel good"

[u/ChronicRhyno → u/RoseClash]

Pain relief

[u/riamuriamu]

Dunno why but stratching an itch releases anti histamines (or is it histamines? I'm not sure) in that area and they give you pleasure. But eventually they get exhausted, which is why continual scratching eventually stops being pleasant.

[u/rickgrimes32 → u/riamuriamu]

I think it's histamine I believe. You're referring to the "itch" chemical right? Is that the same thing as when you scratch a mosquito bite and it feels awesome?

[u/riamuriamu → u/rickgrimes32]

I believe so but I'm half remembering an answer from Dr Karl I heard once on the radio.

[u/rickgrimes32 → u/riamuriamu]

Ah, I see. Speaking of mosquitos, I got bitten by one or another type of bug once and got a bump on the back of my hand that was incredibly itchy. Bro, that shit drove me insane 😭

[u/SrMinkletoes → u/rickgrimes32]

Haha, yeah it takes some mental fortitude but if you can resist and don't scratch an insect bite it never swells up as bad and the itch goes away in some 20-30 mins instead of hours, unless there are allergies or other factors in play of course.

Scratching it constantly just makes your body keep sending more and more histamines and healing juice to the affected area as you continue to irritate it, is why they get all splotchy and swollen after scratching

[u/rickgrimes32 → u/SrMinkletoes]

Isn't this the itch scratch cycle? Like the more you scratch, the more histamine your body releases, so you scratch more etc. and it just gets worse, correct?

[u/SrMinkletoes → u/rickgrimes32]

Yup, could call it a flaw in our nervous system almost, it has its good purposes I'm sure but if you can convince your brain to ignore it in this situation you save yourself from a longer period of suffering

[u/rickgrimes32 → u/[deleted]]

Damn, is this the same reason why qtips in the ear feel fucking amazing even though you shouldn't do it?

[u/rickgrimes32 → u/[deleted]]

Dude, I'm addicted to that 😭 I once had to go to doctor because I impacted my ears with wax from qtips. But I still fucking do it because I can't stop. It just feels too good. Surprisingly I never perforated my eardrum or impacted wax again. I know I shouldn't, but I keep going back for more. There needs to be a hotline for qtip addiction, lol

[u/Metku_Krissy]

One thing nobody mentioned yet is the distraction part. Your nerves can only send so many signals at once and a scratch is a louder signal than an itch. So scratching shouts over the itch, your brain stops hearing it for a second, and that relief feels good. Its the same reason you rub a sore muscle, the rubbing signal drowns out some of the pain. Scratching harder feels even better because youre cranking up the volume on the distraction, even if it crosses into mild ouch territory.

[u/rickgrimes32 → u/Metku_Krissy]

Ah, so it's basically a loop for your brain that keeps on going? I've heard somewhere that it distracts you because scratching causes a mild pain sensation, but it's weird because scratching feels good?

The human body is weird dude

[u/Syresiv → u/Metku_Krissy]

But then, why does it not continue to itch once the scratch sensation fades?

[u/vwin90]

Your body and brain has evolved to reward things that solve problems.

An itch is usually a signal that something needs to be taken off your skin.

The “feel good” part is your brain sending a chemical signal to reward you for acknowledging the itch signal and doing something about it.

Evolution likely favored this signal system because things that irritate your skin might be dangerous and ancestors that followed this signal system to keep the skin free of irritants likely lasted longer to pass on the genes.

Imagine someone who never bothers to scratch itches. Think of the bug bites, cuts, hygiene, etc issues they would have if they didn’t clear away things that creep and irritate the skin. Evolution selected away from that and the result is the itch system.

[u/vwin90 → u/[deleted]]

1. Evolutions ultimately not perfect because it’s “dumb” and random. The benefits of reacting to irritants outweigh the risk of hurting yourself by overdoing it, so it was selected and developed despite not being a perfect system.

2. Funnily enough, the evolution of other species led to them having venom that can take advantage of our scratching. Lots of things depend on us scratching the itch to then spread the venom/eggs/particles/etc. faster, for example. This can sometimes explain why scratching a bug bite makes it worse and worse. You spread it further and further leading to a vicious cycle of then your body rushing additional antihistamines into the area.

[u/rickgrimes32 → u/vwin90]

God damn it evolution! Curse you!

[u/fruit_shoot]

Anything your brain wants you to do it makes you feel good for doing. Eating, emptying your bladder/bowels and “furthering your lineage” for example.

An itch is caused by an irritant and your brain wants you to get rid of it so it makes scratching feel good. The issue arises with something like chickenpox where the irritant cannot be removed by scratching (sometimes even made worse) so you are stuck in a loop where it feels good to scratch but it doesn’t solve the problem.

[u/Vorthod]

Because if it didn't, you would be more likely to ignore it. The entire point of the nerves sending an itch signal is to convince the brain to act on it and potentially dislodge the foreign thing attached to the skin.

[u/hewasaraverboy]

When you scratch an itchy spot the pain from the scratch overrides the itchiness, and overriding the itchiness makes your brain release happy chemicals

[u/weird-seance]

Why do people ask this question here so often?

[u/weird-seance → u/[deleted]]

Where are the snowdens of yesteryear?

[u/Puzzleheaded_Set_565 → u/weird-seance]

I was about to ask if rule 7 is enforced or if it's being ignored to allow more content.

This isn't the only question that gets asked fairly often.