A keloid is a type of raised scar that grows beyond the boundaries of the original wound and doesn’t stop on its own. Unlike a normal scar, which flattens and fades over time, a keloid keeps expanding into surrounding healthy skin, sometimes for months or years after the initial injury has healed. Keloids can form after surgery, piercings, burns, acne, or even minor cuts, and they affect roughly 1 in 30 Black individuals in the United States.
How Keloids Differ From Other Scars
All scars involve the body laying down collagen to close a wound. In a keloid, that process never properly shuts off. The scar-building cells in the skin become overactive, producing up to 20 times more collagen than a normal scar. They also resist the signals that would normally tell them to stop dividing and die off. The result is dense, thick bundles of collagen that pile up well past the wound’s original edges.
The distinction that matters most is between a keloid and a hypertrophic scar, because the two look similar early on. A hypertrophic scar stays within the borders of the wound. It typically appears within four to eight weeks after injury, grows for six to eight months, then plateaus and often shrinks somewhat on its own. A keloid, by contrast, can appear anywhere from three months to several years after injury, spreads horizontally into undamaged skin, rarely matures, and does not regress. If a raised scar is creeping outward past where the wound originally was, that horizontal growth is the defining sign of a keloid.
What a Keloid Feels Like
Keloids aren’t just a cosmetic concern. Somewhere between 50% and 90% of people with keloids experience itching, pain, or both. The itching tends to be worse at the edges of the keloid rather than its center, likely because nerve fibers are packed more densely at the border. The scar tissue itself is stiff and inflexible, which pulls on surrounding nerve endings and creates a chronic low-grade irritation that can produce ongoing discomfort.
Testing on keloid patients has shown measurable differences in how the scarred skin responds to temperature and touch compared to normal skin, a sign that the small nerve fibers within the keloid are functionally impaired. Some people describe the sensation as tenderness or a burning quality rather than sharp pain. Large keloids on joints or the neck can also restrict movement.
Where Keloids Typically Form
Keloids show a strong preference for certain body areas. In a review of 1,000 keloid patients, the most common location was the chest (34%), followed by the shoulders and upper arms (17%), other parts of the upper limbs (13%), lower limbs (10%), and earlobes (9%). The upper back and posterior neck are also common sites. The prevailing explanation is that these areas experience high skin tension and mechanical stress, though earlobes, which have relatively low tension, are a notable exception that suggests other factors play a role.
Who Is Most at Risk
Skin tone is the strongest known risk factor. People of African or Asian descent are far more likely to develop keloids than people of European descent. In the United Kingdom, prevalence estimates run about 2.4% in Black patients, 1.1% in Asian patients, and 0.4% in White patients. In the U.S., the risk for Black individuals is roughly 20 times higher than for White individuals.
Genetics play a role, but the pattern is complicated. Keloids can run in families, yet researchers have not pinpointed a single gene or inheritance pattern responsible. Instead, keloid susceptibility appears to involve many genes acting together, making it a complex trait rather than a simple inherited one. Heritability estimates vary significantly across populations, ranging from about 6% in people of European ancestry to 34% in those of African ancestry. Age also matters: keloids most commonly develop between puberty and age 30, and they occur less frequently in older adults and young children.
Why the Healing Process Goes Wrong
Normal wound healing moves through overlapping phases: inflammation, tissue building, and remodeling. In the remodeling phase, the body is supposed to break down excess collagen and reorganize the scar into something flatter and more flexible. In keloid-prone skin, this remodeling phase is disrupted. Collagen keeps being produced while the mechanisms that break it down are impaired.
The scar-building cells in keloid tissue are unusually responsive to a signaling molecule called TGF-beta, which is found at elevated levels in keloid tissue compared to normal skin. This molecule drives collagen production into overdrive. Other inflammatory signals, including certain immune system messengers, sustain the process by keeping the scar-building cells proliferating and depositing extra structural material. Essentially, the wound stays stuck in a building phase that never transitions to the calming-down phase.
Treatment Options and Recurrence
Keloids are notoriously difficult to treat, primarily because they tend to come back. Surgical removal alone carries a recurrence rate of 50% to 100%, depending on the study, which is why surgery is almost always combined with another therapy.
The most common approaches include:
- Steroid injections into the scar: These reduce inflammation and can flatten smaller keloids. When combined with surgical excision (particularly for ear keloids), recurrence rates have been reported as low as 9.6%.
- Radiation therapy after surgery: Delivering radiation to the excision site in the days following surgery is one of the most effective combinations studied. With appropriate dosing, recurrence can drop below 10% to 20%, compared to the 50% to 80% range with surgery alone.
- Silicone sheets: These adhesive sheets are placed over the scar and worn for extended periods. They’re often used both to treat existing keloids and to prevent new ones from forming after surgery.
- Pressure therapy: Custom pressure earrings or compression garments worn for 6 to 12 months after surgery can help prevent regrowth. This is especially common after earlobe keloid removal.
- Cryotherapy: Freezing the keloid tissue can reduce its size, often used for smaller keloids or in combination with other treatments.
No single treatment works reliably for everyone, and many people go through several rounds of different therapies. The combination of surgical excision plus an adjuvant treatment (steroid injections, radiation, or pressure) consistently outperforms any single approach.
Preventing Keloids if You’re Prone to Them
If you’ve had a keloid before, the most effective prevention strategy is avoiding unnecessary skin trauma. That means being cautious about elective piercings, tattoos, and cosmetic procedures. When surgery is unavoidable, several measures can reduce your risk of a keloid forming at the incision site.
Applying silicone sheets to a new wound as it heals is one of the simplest preventive steps. Steroid injections into a fresh scar during the early healing period can tamp down the inflammation that seems to trigger keloid formation. If the wound is in a high-risk area like the chest or shoulders, pressure garments worn for six months or longer can also help. Starting these measures early, before a keloid has a chance to establish itself, gives the best odds of avoiding one altogether.