The ability of the human body to heal and repair most wounds is truly remarkable; from small cuts and scrapes to larger injuries and ailments, our bodies seem to be on a constant mission to keep us 100% intact and healthy.
However, a peculiar thing happens when our wounds are healing – the unavoidable “itchiness” of the wound. In particular, this happens after scabs have begun to form and the healing process is moving in the right direction. For many people, scratching that itch is far too satisfying to avoid, which can often disrupt the healing process, making it take even longer!
If the human body is clever enough to heal itself, then why does it also make those wounds so itchy?
The Healing Process
For those who think the itch of a healing wound is just one of Nature’s great practical jokes, I’m here to burst your bubble. It is actually a normal side effect of one of the body’s natural healing stages.
When our body sustains a wound, a number of chemical and physical processes almost immediately begin to protect our bodies from infection and pain. A wound will initially bleed, flooding the space with chemicals and fluids to clean the area and set the stage for healing to begin. Following this, the wound will become inflamed, which is a sign that white blood cells have reacted to the potential for infection; additional cleansing of the wound happens at this point, in addition to preliminary repairs on the skin bed.
Those first two stages (bleeding and inflammation) are typically considered “painful”, but in the third stage, the tissues begin to regrow, blood vessels are repaired, and a scab begins to form over the healing wound. This part of the healing process is where the itchiness begins, and to understand an itch, we need to look at the nerves.
Chemical and Physical Causes of an Itch
Every square inch of our skin is connected to nerves, which provide us with our sense of touch and sensitivity to external stimuli. There are also many itch-specific nerve fibers located on our body’s largest organ. These fibers tell our central nervous system that something is irritating the skin in a certain spot, with the intention of eliciting a response from the body (scratching the itch).
Physically speaking, these fibers are activated near the end of the healing process (in the proliferative stage), when a scab begins to form. When our body sustains a wound, new cells are formed near the edges of the injury and then move down to the base of the wound. Once these cells have migrated to the deepest parts of the wound and found their new home, they connect with other cells that are nearby. Once this connection is made, the cells contract, effectively “closing the wound”.
Now, during this contraction process, those itch-sensitive nerve fibers are activated, sending signals to the brain that something is irritating the body at that location, quietly urging us to give the spot a hearty scratch.
Our urge to itch isn’t purely physical, however; there is also a chemical component to this sensation. Our body works in many ways to induce healing and promote better health, and the release of certain chemicals at the site of a wound is one of these methods. Those chemicals aren’t typically found in those places, and the presence of those compounds also stimulates the activity of those itch-sensitive nerve fibers.
As with many things in anatomy and nature, there are multiple sides to the story. We may be annoyed when a freshly healed wound stimulates a battle of scratching willpower in our minds, but that very same activity of our nervous system, signaling that “something is wrong”, is also what helps our body protect and heal itself.
Those nerve fibers that tell us to scratch an irritated area of the skin can help us avoid dangerous substances, plants, and the potentially dangerous bite of an insect. The internal chemical irritant that sends us scratching promotes health by speeding up the healing process and helping us avoid infection and extended periods of pain.
The fact that our wounds itch when they’re healing is a good sign; it means that our body’s chemical and mechanical processes are working properly. However, it’s always helpful to have a partner who can help scratch your hard-to-reach places.
Now, if we could just muster a bit of willpower and stop ourselves from picking off that scab, life would be grand!
- Go Ask Alice!- Columbia University
- Health Information from the National Library of Medicine
- TED-Ed (Sarthak Sinha) Youtube