Keloid or Hypertrophic Scar: How to Tell the Difference

Two raised scars that are easy to mix up

You have a scar that sits above your skin. It may feel firm, itch or feel sore, and you want to know what it is before you spend money on it. Most raised scars turn out to be one of two kinds: a hypertrophic scar or a keloid.

Both form when the body makes more collagen than it needs while a wound heals. A 2023 medical review in the journal Cells puts the main difference plainly: in a hypertrophic scar the extra scar tissue stays at the site of the injury, while a keloid can extend beyond the original wound. The keloid glossary entry has a short definition if you want the basics first.

Telling them apart matters because they behave differently over time and are often treated differently. This guide only covers how to tell them apart. The treatments themselves are compared side by side in raised scar treatments compared.

The border and the calendar

Look at the edges first. A hypertrophic scar follows the shape of the cut, burn, piercing or breakout that caused it. A keloid spreads onto healthy skin around the wound, and the American Academy of Dermatology (AAD) says a keloid can range from the size of a pimple to larger than a football. On the ear, neck or belly, a keloid may even hang from the skin.

Then think about timing. Hypertrophic scars usually show up within a few weeks of the injury. For acne, the AAD says a hypertrophic scar tends to appear 1 to 2 months after a breakout clears. Keloids are slower to start: the AAD says it often takes 3 to 12 months or longer to see the first sign, which is usually thickening skin, and that about 20% of keloids appear more than a year after the injury.

Last, notice which way it is heading. A 2021 review in Plastic and Reconstructive Surgery describes hypertrophic scars growing for about 3 to 6 months and then leveling off and slowly shrinking when risk factors are minor. The AAD notes that raised scars tend to flatten, though it can take months or years. Most keloids keep growing for weeks or months, and a few grow for years. Once a keloid stops growing it tends to stay the same size, and the AAD says it rarely fades without treatment.

The same review adds an honest caveat: many scars have features of both, so doctors see the two as ends of a spectrum rather than two neat boxes.

Who is more likely to get a keloid

Anyone can get a hypertrophic scar after a deep wound, burn or surgery, especially where the skin is pulled by movement, such as the chest, shoulders, upper back and joints. Keloids are more selective. The AAD lists these factors that raise the risk:

• Skin color and ancestry. In the United States, keloids are more common in Black and Latin American people than in people with lighter skin tones.
• Family history. About one-third of people who get keloids have a parent, brother, sister or child who also gets them.
• Age. The AAD says Black people between the ages of 10 and 30 have the greatest risk of developing a keloid.
• Pregnancy. Hormone changes during pregnancy raise the risk.
• A past keloid. If you have had one, you can develop another in the future.

Checks you can do before your visit

You cannot diagnose your own scar, but you can bring useful facts to the person who will. A short record helps a provider see which way the scar is behaving.

Write down when and how you were injured and when you first noticed the scar rising. Take a clear photo every few weeks in the same light, with a ruler or coin beside the scar, so you can see whether it is spreading past its first outline. Note any itching, pain, burning or tightness, and whether anyone in your family has keloids.

Bring a list of any earlier treatments, such as silicone sheets, creams or injections, and how the scar responded. The AAD says it is important for the person treating a keloid to know how your skin responded to past treatment. If you have darker skin or a history of keloids, the guide on scar and pigment treatment for darker skin explains why careful settings and test spots matter.

When a raised scar needs a doctor first

Most keloids are harmless, according to the AAD, but a few situations call for a dermatologist rather than a cosmetic visit. A keloid that has opened, will not heal or looks infected should be seen promptly. So should a scar that is growing quickly, bleeding without an injury, changing in color or shape, or very painful.

Be especially careful with a scar that appeared where you never injured your skin. The AAD advises seeing a dermatologist right away in that case, because skin cancer can sometimes look like a scar. The 2021 review notes that a few rare tumors can be mistaken for keloids, which is why doctors may take a small skin sample (a biopsy) when something looks unusual. If your scar is from a recent surgery, check with your surgeon before starting any outside treatment.

Pregnancy is another reason to pause. The AAD lists it as a time of higher keloid risk, and Laser Eraser's candidacy screening notes that pregnancy means waiting before elective treatment. If a raised scar appears during pregnancy and is not growing fast or changing, you can photograph it and have it examined after the baby arrives.

What happens next at Laser Eraser

At a free consultation, a licensed medical provider looks at your scar and confirms which type it is before recommending anything. At Laser Eraser, keloids are treated with a series of injections into the scar, not with the laser, as the keloid scar treatment page explains. Raised scars that stay within the wound are covered on the hypertrophic scar treatment page.

If your scar is still new, timing may matter as much as type. The guide is your scar ready for treatment covers how long scars usually take to settle and when waiting makes sense.