How come rubbing alcohol burns when applied to open cuts and wounds, but hydrogen peroxide does not?
In: Biology
You have nerves in your body that are there to sense temperature and tell you if you the temperature of something touching your skin is too hot. These nerves have a level where they will fire once the temperature gets above this threshold. So let’s say the threshold is 120 degrees. If you touch something that is 100 degrees, the nerves won’t fire. But if you touch something that’s 180 degrees, the nerve fires and sends a message to the brain. The brain gets the message, reads it as “this is hot,” and then sends back a pain message saying “don’t touch that, it hurts.” Now, when you get a cut and put alcohol on it, the alcohol (being the sly, sweet-talking scoundrel that it is) tricks the nerve into thinking it should fire at a lower temperature. Let’s say 90 degrees. So what’s the problem? Your body is 98.6 degrees! So your body’s own heat causes the nerves to fire and send the same signal to the brain that it would if you were actually being burned. Hydrogen peroxide is not nearly as convincing as alcohol, so the nerves don’t fire and it doesn’t create that burning sensation.
Side note: as others have said, there is evidence that you shouldn’t use hydrogen peroxide on cuts because, while it will kill the bacteria, it will also kill your cells and slow the healing process.
Latest Answers