Raised acne scars: hypertrophic scars and keloids

A raised acne scar is a firm bump left where a breakout healed. It forms when the skin makes too much collagen, the protein that gives skin its support, while it repairs the damage. Raised scars are less common than the sunken dents most people picture when they think of acne scars, and they need different treatment. This guide covers the two main raised types, hypertrophic scars and keloids, plus a third, smaller type called a papular scar. It explains how to tell them apart, what dermatologists do, and what you can safely try at home. For every acne scar treatment, see acne scar treatment.

A flat red, pink, brown or bluish gray spot is a different thing. The American Academy of Dermatology (AAD) calls that post-inflammatory hyperpigmentation and says it usually fades. If the spot has a smooth, flat surface, see dark marks after pimples instead.

Who gets raised acne scars

The AAD says raised acne scars are "more common in people who have darker skin tones." A 2017 review in the journal Scars, Burns and Healing says 80 to 90 percent of people with acne scars have sunken scars, and that the smaller group with hypertrophic scars and keloids more often has them on the chest and shoulders.

For keloids, the sources name clear risk factors:

• Skin tone and family. The AAD says Black people have the greatest risk, and that people of Asian, Latin American or Mediterranean descent also have a higher risk than people with lighter skin. It says "between 33% and 50% of people who develop a keloid have at least one blood relative who gets keloids."
• Age. The AAD says ages 10 to 30 are "the peak time to develop keloids." The NHS gives the same range.
• Pregnancy. Both the AAD and the NHS list pregnancy as a risk.
• A past keloid. The NHS lists having had a keloid scar before.

The AAD's list of keloid causes includes a "bout with acne or chickenpox (usually developing on the face, chest, or back)."

Hypertrophic scar or keloid?

The two look alike at first. The difference is whether the scar stays inside the area of the original breakout.

	Hypertrophic scar	Keloid
When it appears	Often 1 to 2 months after a breakout clears (AAD)	First sign is thickening skin, usually 3 to 12 months after acne clears (AAD)
Size	Stays within the original wound (NHS)	Grows larger than the breakout that caused it (AAD)
Over time	"Usually fades and flattens over time" (NHS)	"Doesn't fade with time" (AAD)
Where on the body	Jawline, chest, back (AAD)	Chest, shoulders, chin, neck, lower legs and ears (NHS)
Feel	Firm (AAD)	Hard and rubbery or soft and doughy (AAD); may itch or hurt while growing

The AAD says a keloid "tends to grow slowly for months or years," and that "once a keloid stops growing, it tends to remain the same size." MedlinePlus, from the U.S. National Library of Medicine, adds that a keloid "will tan darker than the skin around it if exposed to the sun during the first year after it forms. The darker color may not go away."

Papular scars

The AAD describes a third raised type. A papular scar is "skin colored or lighter than the person's natural skin tone," usually on the nose, chin, jawline or back, and "can be mistaken for acne." The AAD says "dermatologists use lasers to treat raised acne scars called papular scars."

How dermatologists treat hypertrophic acne scars

The AAD explains why raised scars need their own plan: "Raised scars develop when the body produces too much collagen, so they require different treatment." For hypertrophic acne scars, it says a dermatologist may recommend:

• Laser treatments. The AAD's general scar page says lasers can "reduce the appearance of existing raised scars and keloids" and lessen redness, itch and hardness.
• Injections into the scar. A corticosteroid, a medicine that calms inflammation, is the most common choice. The AAD says it can "reduce the size of a scar by 50% or more." Possible side effects include "the scar returns, thinning skin, and dark spots where you had the injection." Most people need more than one treatment.
• A prescription medicine applied to the scar. The dermatologist chooses which one.

The AAD's general scar page says many scars can be treated "if they make you feel uncomfortable around others, cause pain, or restrict your movement." Treatment is a choice, and a dermatologist can tell you whether a scar is likely to flatten on its own.

How dermatologists treat keloids

The AAD says: "To give their patients the best results, dermatologists often recommend more than one type of treatment for a keloid. These scars can be difficult to get rid of, and some return after treatment." Its keloid treatment page lists the options:

Treatment	What the AAD says
Corticosteroid injections	"Between 50% and 80% of keloids shrink after being injected. Many of these keloids, however, will regrow within five years." On darker skin, light spots can form at the injection site
Keloid surgery	"Nearly 100% of keloids return" after surgery alone, so another treatment follows
Freezing (cryosurgery)	Works best on small keloids. Can cause a permanent light spot on brown or black skin
Laser	Can reduce the height and fade the color, often with injections or pressure
Pressure garment or earring	Worn 12 to 20 hours a day for several months, often after surgery
Silicone gel sheets	May help flatten a keloid and prevent it from returning after treatment
Radiation	Used after surgery to lower the chance of return; the AAD lists skin changes and cancer reports among its drawbacks

The NHS adds that "surgery to remove the keloid scar is not usually recommended because it's likely to grow back bigger." MedlinePlus warns that these treatments, "especially surgery, sometimes cause the keloid scar to become larger." Results vary, and the AAD says "no treatment can consistently get rid of a keloid."

What the steroid injection label says

The corticosteroid injected into keloids is often triamcinolone. The FDA-approved label for Kenalog-10, one triamcinolone injection, lists keloids among the conditions it is approved to treat by injection directly into the problem area. The label tells doctors to choose the site and amount carefully "due to the potential for cutaneous atrophy," which means thinning of the skin. Its list of skin side effects includes thinning, lighter or darker skin, and thin, fragile skin. That matches the AAD's warning about light spots on darker skin.

What you can do at home

Silicone gel sheets. These are thin, sticky sheets made of medical-grade silicone that you can buy without a prescription. The AAD says silicone can "treat a raised scar by reducing its size, hardness, redness, swelling, itch, or stiffness," and that sheets appear to work better than silicone ointment. The drawback is time: "To get results, you must wear a gel sheet every day, often for months." Wearing one in the same place every day can cause a rash or skin breakdown, so stop and tell a dermatologist if that happens. Never put a sheet on a scab or open wound.

The evidence is mixed. A 2013 Cochrane review of 20 trials found silicone gel sheeting reduced scar thickness and improved color, but said the trials were "of poor quality" and open to bias.

Sun protection. The AAD says the sun can darken a scar, and a keloid's darkening "can be permanent." Cover the scar with clothing or use sunscreen with SPF 30 or higher.

Creams sold for scars. The AAD says research on non-prescription scar products with onion extract, vitamin A or vitamin E "is limited," and advises talking to a dermatologist first. Skinli's guide to home remedies for acne scars covers what else people try.

Treatments to check before you book

Some scar treatments carry risk for people who form keloids:

• Microneedling. The AAD says you should not have microneedling if you "have (or had) a raised scar called a keloid." The FDA says the procedure may not be suitable for people with keloid scars "or a history of keloid scars." See microneedling for acne scars.
• Fillers. The FDA says the safety of dermal fillers "is unknown in patients who are prone to excessive scarring (keloids or hypertrophic scars)." See dermal fillers for acne scars.
• Any cosmetic procedure. The AAD's keloid self-care page says a cosmetic procedure injures the skin, so a person prone to keloids could get one afterward. It suggests telling the doctor first and trying a small test spot.

Preventing keloids from acne

The NHS says it's "recommended to get early treatment for acne to reduce the risk of scarring." Treat breakouts early and leave them alone, because the AAD says picking and squeezing raise the risk of scars. The free Skinli acne plan sets out a routine with benzoyl peroxide 2.5 percent and adapalene 0.1 percent. If you have had a keloid, watch healed breakouts on your chest, back and jaw. The AAD says that "if you notice thickening skin, wearing a pressure garment can prevent (or reduce the size of) a keloid."

When to see a dermatologist

See a dermatologist if a raised scar keeps growing, itches or hurts, or bothers you. The NHS says "getting treatment early may help stop the keloid scar growing." The AAD says a keloid that opens and does not heal needs a dermatologist, and that a scar you do not remember getting should be checked, because skin cancer can look like a scar. Skinli gives general education and is not a doctor. For raised scars on the back and chest, see back acne scars.