Encountering a sudden bump on the skin is a common experience. While many are familiar with blemishes like zits or pimples, it’s intriguing why some cause discomfort or pain, while others go unnoticed. This variation prompts a closer look into the biological processes distinguishing painful from painless zits.
What Causes a Zit
A zit begins its formation within the skin’s hair follicles, which are small openings containing a hair shaft and a sebaceous gland. These glands are responsible for producing an oily, waxy substance called sebum, which serves to lubricate and protect the skin and hair. Normally, sebum flows freely to the skin’s surface, along with dead skin cells that are continuously shed.
However, a zit forms when excess sebum and dead skin cells accumulate and clog the opening of a hair follicle. This blockage creates an environment where bacteria, particularly Cutibacterium acnes (formerly known as Propionibacterium acnes), can multiply rapidly. While Cutibacterium acnes is a normal inhabitant of the skin microbiome, its overgrowth within a clogged pore contributes to the development of a zit.
The Science of Zit Pain
Painful zits are characterized by an inflammatory response. When a hair follicle becomes clogged and bacteria proliferate, the body’s immune system reacts. This immune response leads to inflammation, manifesting as redness, swelling, and warmth. Inflammation drives pain by releasing chemical mediators that sensitize nerve endings.
The accumulation of pus, dead cells, and excess oil within the confined space of a blocked follicle also creates internal pressure. This pressure builds up, pushing against the surrounding skin tissues and pressing on nearby nerve endings. This mechanical pressure directly contributes to the sensation of pain.
The depth and location of a zit play a significant role in its painfulness. Deeper lesions, such as cysts and nodules, extend into the skin’s dermal layers, which have a higher concentration of nociceptors. These specialized nerve endings detect and transmit pain signals to the brain. When these deeper tissues and nerve endings are involved, the pain is often more intense.
Why Not All Zits Hurt
Not all zits result in pain, especially superficial types like blackheads and whiteheads. These blemishes are considered non-inflammatory lesions. Blackheads, or open comedones, occur when a pore is clogged but remains exposed to air. Melanin in dead skin cells reacts with oxygen, causing the dark appearance, but without significant inflammation or pressure.
Whiteheads, or closed comedones, form when the pore is completely blocked beneath the skin’s surface. They involve a buildup of sebum and dead skin cells, but the contents are contained superficially without creating substantial pressure on deeper tissues. Since these zits do not involve a strong immune response or significant pressure on nerve endings, they do not cause discomfort. Their shallow depth means they do not reach the deeper, more sensitive nerve networks that contribute to pain in inflamed lesions.