Keloid vs Hypertrophic Scar: What Is the Difference, Which Treatments Work, and Why Cutting a Keloid Out Often Makes It Grow Back Bigger
Keloid is a scar in which the body makes too much collagen, so it becomes raised and firm, grows beyond the edge of the original wound onto normal skin, and rarely flattens on its own. A hypertrophic scar is also raised but stays within the boundary of the original wound, and it usually flattens gradually on its own within 1–2 years.
The two conditions look very similar, but the outlook and the treatment differ, especially when it comes to surgery. A hypertrophic scar can be revised surgically with relatively low risk. A keloid that is simply cut out without additional treatment comes back in about 45–100% of cases, and often grows larger than before. This article covers keloids by their common locations, names the medicines doctors actually use, their strengths, the spacing between injections, and the signs that treatment is or is not working.
How Is a Keloid Different from a Hypertrophic Scar?
The easiest way to tell them apart is to check whether the scar extends past the edge of the original wound, and whether it shrinks or keeps growing as time passes.
Boundary: a hypertrophic scar stays within the original wound line, while a keloid spreads beyond it, sometimes forming a crab-shaped lump with claw-like extensions to the sides.
When it appears: a hypertrophic scar usually rises within 4–8 weeks of the injury, while a keloid may begin to rise later, anywhere from 3 months to a year afterward.
Trend: a hypertrophic scar usually flattens and fades on its own within 12–24 months, while a keloid usually keeps growing slowly or stays the same and rarely shrinks by itself.
Symptoms: both can itch and hurt, but a keloid tends to itch or sting more, especially when you sweat or when clothing rubs against it.
Location: a hypertrophic scar can occur anywhere the wound is under tension, such as over joints and in burn scars, while keloids favour the earlobes, chest, shoulders, upper back, and jaw.
After surgical removal: a hypertrophic scar usually improves after the scar line is surgically revised, while a keloid has a very high chance of returning if it is cut out without additional treatment.
In practice, a scar younger than 1 year sometimes cannot be clearly classified. The doctor considers your history, the location, and how the scar changes over time. If it cannot be told apart, doctors usually treat it as a keloid first, because that is safer than operating right away.
What Do the Early Signs of a Keloid Look Like?
An early keloid often does not look like a lump. It looks like a wound that should have healed but is not smooth. Signs to watch for are
The wound has fully closed but is still red or dark pink after 6–8 weeks
The scar begins to feel thicker and firmer than the surrounding skin
Intermittent itching in the scar, or a stinging pain when clothing touches it
A small firm bump, 2–3 mm, in front of or behind an earlobe piercing that does not go down even after the earring is removed
The edge of the scar starts to extend onto normal skin
If you notice these signs and you have had keloids before or have family members with them, see a dermatologist now. A keloid smaller than 1 cm and less than 1 year old responds to injections better than an old, very large lump.
What Causes Keloids, and Who Is at Risk?
A keloid develops when fibroblasts in the wound do not stop working. They keep producing collagen after the wound has closed, together with lingering inflammation in the dermis. Skin tension makes the process worse, which is why keloids are common where the skin is constantly stretched, such as the chest, which moves with every breath.
Clear risk factors include
Genetics: having a parent or sibling with keloids clearly raises the risk.
Skin colour: people with darker skin, including Asians, develop keloids more often than people with fair skin.
Age: keloids are most common between the ages of 10 and 30, and less common in young children and older adults.
Hormones: during adolescence and pregnancy, keloids may grow faster.
Type of wound: wounds with prolonged inflammation, infection, or healing that takes longer than 3 weeks, such as burns, deep inflamed acne, chickenpox, and surgical wounds under tension.
Someone who has had a keloid in one location can develop one again in a new wound elsewhere, so tell your doctor every time before surgery, ear piercing, or any procedure on the skin.
Hypertrophic Scar After Surgery or Burns
Appearance: raised and red or pink, following the original wound line exactly and not spreading beyond the edge. It is usually a line, or a patch matching the shape of a burn, and it may pull on a joint so that it cannot fully straighten.
Cause: a wound under tension, an infected wound, or a wound that heals slowly, especially burns that take more than 2–3 weeks to heal.
Severity and urgency: not dangerous. Most flatten on their own within 1–2 years, but if the scar pulls on a joint and limits movement, do not wait.
When to see a doctor: the scar is still raised and red after 3 months, itches so much that it disturbs sleep, or tightens the wrist, elbow, or neck.
Hypertrophic scars are the group that responds best to silicone sheets and pressure. If you start early, in the first 2–3 months, the scar flattens noticeably faster. For details on choosing silicone gels and sheets, read Scar Creams: Which One to Choose and How Long to Apply.
Earlobe Keloid from Ear Piercing
Appearance: a round, firm lump with a smooth, shiny surface, at the front, the back, or both sides of the piercing, ranging from the size of a bean to 2–3 cm. Some people have it on both ears.
Cause: an injury from piercing the earlobe or ear cartilage, especially when the piercing becomes inflamed or infected early on, or when a metal allergy in the earring causes chronic inflammation.
Severity and urgency: not dangerous, but it usually keeps growing slowly. The longer you wait, the larger the lump and the harder it is to treat.
When to see a doctor: a firm bump at the piercing that has not gone down within 4–6 weeks after removing the earring, or a lump that keeps getting bigger.
The earlobe is the one location where surgery combined with additional treatment works relatively well, because the earlobe is easy to compress with a pressure earring after surgery. Doctors usually inject steroid into the surgical wound repeatedly every 2–4 weeks and have the patient wear a pressure earring 12–24 hours a day continuously for 6–12 months. Someone who has had an earlobe keloid should not get any new ear piercings.
Keloid on the Chest and Shoulders
Appearance: a firm, raised, dark red lump, often butterfly-shaped or crab-shaped in the middle of the chest, or a plaque on the shoulder, spreading sideways along the direction of skin tension.
Cause: inflamed acne, scratches, a chest surgery wound, a vaccination on the upper arm, or in some people it appears with no clear wound at all (spontaneous keloid).
Severity and urgency: this is the location where keloids grow fastest and come back most often. They usually itch and hurt a lot.
When to see a doctor: while the lump is still small. Do not wait for it to spread, and do not have it cut out without a plan for additional treatment.
For the chest and shoulders, most dermatologists avoid surgery as the first treatment, because the tension from breathing and arm movement turns a fresh surgical wound into a keloid larger than before. The main treatment is repeated injections into the lump, together with silicone sheets.
Acne Keloids on the Back, Jaw, and Chin
Appearance: multiple firm raised bumps scattered along areas that previously had inflamed acne, such as the jaw, chin, upper back, and chest. Some bumps are as small as a mung bean and some merge into plaques.
Cause: deep inflamed acne, large cystic acne, and squeezing or picking at pimples, which pushes the inflammation deep into the dermis.
Severity and urgency: if inflamed acne is still active, new keloids keep forming, so the acne has to be controlled at the same time.
When to see a doctor: firm bumps that have not gone down more than 2–3 months after the acne has cleared, or deep inflamed acne bumps that are still present.
The core of treating acne keloids is to stop the inflamed acne first. Otherwise, you flatten the old spots only for new ones to form. Read how to control inflamed acne in Inflamed Acne: Causes and How to Treat It Without Scarring and Cystic Acne: Can You Pop It?. Acne that has healed and left a sunken pit is not a keloid; see Acne Pits: Can They Really Be Filled In?
Keloid After Surgery, C-Section, and Injury Wounds
Appearance: a surgical wound that becomes thick and raised 2–6 months after the operation. At first it looks like a hypertrophic scar, but it gradually spreads beyond the suture line.
Cause: a wound under tension, an infected wound, loosened stitches, or a wound that runs perpendicular to the direction of skin stretch.
Severity and urgency: not dangerous, but treatment while the scar is still red responds better than treatment of an old scar.
When to see a doctor: a surgical wound that is still raised, red, and itchy after 3 months, or if you know you form keloids easily and are about to have surgery.
People with a history of keloids who are planning surgery, such as a second C-section, should tell the surgeon in advance. Commonly used prevention plans are to close the wound with as little tension as possible, to start silicone sheets once the wound is fully closed (about 2 weeks after surgery), and in some cases to have the doctor inject steroid into the wound early on.
Bumps on the Back of the Neck After Shaving (Acne Keloidalis Nuchae)
Appearance: multiple small firm bumps at the back of the neck below the hairline. In some people they merge into a raised band across the neck, with pus or ingrown hairs.
Cause: chronic inflammation of hair follicles from shaving or clipping the hair close to the scalp, and collar friction. It is common in men with curly hair.
Severity and urgency: this is a different condition from a typical keloid, despite the similar name. If you keep shaving the hair short, it keeps progressing.
When to see a doctor: bumps on the back of the neck for more than 1 month, or repeated pus.
Treatment starts with stopping close shaving, together with medicine to reduce follicle inflammation, such as a topical steroid, 1% clindamycin applied to the skin, or oral doxycycline, as assessed by the doctor. Bumps that have become firm are then treated with steroid injections, like a keloid.
Is a Keloid Dangerous? Can It Turn Into Cancer?
A keloid is an overgrowth of scar tissue that is not cancer and does not turn into cancer. It does not spread to other organs. The main problems are itching, pain, tightness, and the effect on confidence.
However, in some cases a lump looks like a keloid but is not one. A doctor will consider a skin biopsy when
The lump appears on its own without a previous wound and grows unusually fast within a few months
The lump has an open sore, bleeds easily, or has several colours within one lump
The lump does not respond at all after 3 injections
The lump is in a place where keloids do not normally occur, such as the palms or soles
Some tumours, such as dermatofibrosarcoma protuberans (DFSP), look like a keloid in the early stage. A small biopsy can clearly tell them apart.
Steroid Injection into a Keloid (Triamcinolone Acetonide)
Injecting steroid into the lump is the main treatment for keloids and for hypertrophic scars that do not go down on their own. The medicine used is triamcinolone acetonide, which reduces inflammation and reduces collagen production in the lump.
Strength: 10–40 mg/mL. The doctor chooses according to the thickness of the lump. Thin lumps or lumps on the face use 10 mg/mL. Thick, firm lumps on the chest or earlobe use 20–40 mg/mL.
Spacing: every 4–6 weeks (in some people as often as every 2–3 weeks at the start).
Number of sessions: most people need 3–6 injections or more before the lump clearly flattens.
When you see results: itching and pain usually decrease after the first injection. The lump starts to soften and flatten after 2–3 injections.
How well it works: the lump flattens partially to almost completely in about 50–100% of patients, but it can regrow in about 9–50%, so follow-up is needed.
Side effects to know about before injection are skin that sinks below the level of the surrounding skin (atrophy), lighter skin around the lump (hypopigmentation), and visible small blood vessels, especially with high strengths or when the medicine leaks outside the lump. Most gradually improve within 6–12 months. Some women have temporary menstrual irregularity after large doses. Stopping the injections once the lump is level with the skin, and leaving enough time between sessions, helps reduce these side effects.
Other Injections When Steroid Alone Is Not Enough: 5-FU, Verapamil, Botulinum Toxin
If the lump flattens by less than half after 3–4 steroid injections, or the skin around it starts to thin and lighten, the doctor may switch or add another medicine.
5-fluorouracil (5-FU) 50 mg/mL: inhibits fibroblast proliferation. It is often mixed with triamcinolone at a 9:1 ratio (0.9 mL of 5-FU with 0.1 mL of triamcinolone 40 mg/mL) and injected every 1–4 weeks. In several studies it worked better than steroid alone and caused less skin sinking. It hurts more during injection and may cause shallow sores or darkening at the injection site. Do not use during pregnancy or breastfeeding.
Verapamil 2.5 mg/mL: a medicine injected into the lump every 3–4 weeks. It is an option when you want to avoid skin thinning from steroids. It works a little more slowly.
Botulinum toxin type A: reduces tension in the muscles around the scar and reduces itching. It is used as an add-on for scars in areas that move a lot. There is less data than for the first two medicines.
All of these must be injected by a doctor, and the choice of medicine, strength, and mixing ratio is decided by the doctor based on the size, location, and previous treatment history of each person.
Silicone Sheets and Gels: How Long to Use Them
Silicone has the best evidence among treatments you can use at home. It works by keeping the skin hydrated and reducing the signals that stimulate collagen production.
When to start: once the wound is fully closed, with no scab and no oozing, usually about 2 weeks after surgery or after the stitches are removed.
Hours per day: silicone sheets are worn 12–24 hours a day and removed once a day for washing. Silicone gel is applied in a thin layer twice a day.
How long: at least 12 weeks, and many people need 6 months or more.
Signs it is working: the scar becomes softer, the redness fades, and itching decreases within 4–8 weeks.
Silicone alone helps hypertrophic scars and recently formed keloids well, but it rarely flattens a large keloid that has been there for years. For old lumps, silicone is an add-on after injections or after surgery to reduce recurrence.
Compression Garments and Pressure Earrings (Pressure Therapy)
Continuous pressure reduces the blood and oxygen supply to the collagen-producing cells, which makes the scar flatten. It is widely used for burn scars and earlobe keloids.
Pressure: about 24–30 mmHg. It must be firm enough but must not make the fingertips or skin pale or numb.
Time: 12–24 hours a day.
Duration: 6–12 months.
Where it is practical: the earlobe (pressure earring), and the arms, legs, and trunk after burns (custom-made compression garments). The chest and shoulders are hard to compress.
The main limitation is that it has to be worn consistently. If it is worn on and off, the results drop a lot.
Treating Keloids with Cold (Cryotherapy)
Freezing with liquid nitrogen, by contact or spray, kills tissue in the lump so that it shrinks. It works well for small to medium lumps and is often combined with steroid injections, because after freezing the lump swells and softens and is easier to inject.
It is done every 3–4 weeks. An important drawback for Asian skin is that the skin at the treated spot often turns lighter, leaving a white patch, and this may be permanent, so it is rarely used on clearly visible areas such as the face, or in people with very dark skin.
Can Lasers Treat Keloid Scars?
Lasers can help, but they are an add-on treatment, not the main treatment for keloids, and the type has to match the problem.
Vascular laser: reduces redness and blood vessels in scars that are still red, helps reduce itching, and softens the scar. It works well for hypertrophic scars no older than 1 year, usually done every 4–6 weeks for 3–5 sessions.
Fractional laser and carbon dioxide laser: make tiny holes in the scar so the skin can remodel, and help medicine applied or injected afterwards penetrate deeper. Used for thick hypertrophic scars or burn scars.
What should not be done is using a carbon dioxide laser to cut or burn off the whole keloid as the only treatment, because it comes back at a high rate, no different from surgery alone. A side effect that can occur is post-laser darkening (PIH), which is common in Thai skin. Results vary from person to person and several sessions are needed. For dark or red marks that are not raised, read about them separately in Acne Marks: Telling Red Marks from Dark Marks.
Why Does Cutting Out a Keloid Often Make It Grow Back Bigger?
Cutting out a keloid creates a new wound in someone whose body responds to wounds by making too much collagen. A new wound that is longer than the old one therefore has a chance of becoming a keloid larger than before. Rough figures from studies are as follows.
Surgery alone: recurrence in about 45–100%.
Surgery followed by repeated steroid injections into the wound: recurrence falls to about half or less, depending on the location.
Surgery followed by radiation to the wound within 24–48 hours: recurrence in about 10–20%. This is used for large keloids that resist other treatments, is done at a hospital with a radiation therapy unit, and is not used in children or pregnant women.
A doctor will consider surgery when the lump is very large, has a stalk (for example an earlobe keloid hanging as a pendant), or has not responded to injections, and the additional treatment after surgery must be planned from the start, not cut first and see later.
How to Make a Keloid Shrink: A Treatment Plan by Size and Age of the Lump
There is no single method that suits everyone. The approaches dermatologists commonly use, grouped by the type of lump, are as follows.
Hypertrophic scar younger than 3–6 months and still red: silicone sheets or gel for 12 weeks or more, together with pressure if possible. If there is no improvement in 2–3 months, add low-strength steroid injections.
Keloid smaller than 1–2 cm: inject triamcinolone 10–40 mg/mL every 4–6 weeks together with silicone until the lump is level with the skin.
Keloid that has flattened by less than half after 3–4 steroid injections: switch to 5-FU mixed with triamcinolone, or add cryotherapy or laser.
Earlobe keloid or a large stalked lump: surgical removal, then steroid injections into the wound every 2–4 weeks together with a pressure earring for 6–12 months.
Large keloid that keeps coming back: surgery combined with radiation after surgery, referred to a hospital with radiation therapy.
A realistic goal is for the lump to flatten, soften, stop itching and hurting, and be kept from growing further. No method guarantees a complete cure or that it will never come back. People who respond well should follow up with the doctor every 3–6 months in the first year, because repeating injections as soon as the lump starts to rise again is easier than waiting until it is large.
How Many Days Until a Scar Fades?
Every wound goes through a healing phase that lasts longer than most people expect.
0–3 weeks: the wound closes, and the new skin is still thin and red.
3 weeks–3 months: the scar is at its reddest and may rise. This is when hypertrophic scars and keloids start to show themselves.
3–12 months: a normal scar gradually fades and flattens.
12–24 months: the scar settles, and its colour gets closer to normal skin.
So a scar that is 2 months old and still red is not always abnormal. But if the scar keeps getting thicker or starts to spread beyond its edge, have a doctor assess it without waiting for a full year. For a fresh wound that has not yet closed, caring for it so it heals quickly is the best way to prevent scarring. Read how to wash and cover a wound in Scrapes: How to Wash, Whether to Cover, and How Many Days to Heal.
Preventing Keloids After Ear Piercing, Surgery, and Acne
For people who know they form keloids easily, prevention always works better than treatment later.
Avoid ear piercings, tattoos, or cosmetic procedures that are not necessary, especially on the chest, shoulders, and earlobes.
If you need surgery, tell the surgeon about your keloid history so that low-tension closure and additional treatment can be planned before the operation.
Care for the wound so it heals quickly and does not get infected: wash it clean, keep it covered and moist, and do not pick at the scab.
Start silicone early as soon as the wound is fully closed, and use it continuously for at least 12 weeks.
Control inflamed acne early and do not squeeze or pick at pimples on the chest, back, and jaw.
Protect new scars from the sun for the first 6–12 months to reduce darkening (sunscreen does not directly prevent keloids, but it helps the scar colour blend in better).
When to See a Dermatologist About a Keloid
A scar is still raised and red after 3 months, or starts to spread beyond the original wound edge
A firm bump at an ear piercing that does not go down
Itching or pain that disturbs sleep or daily life
A scar that pulls on a joint so that it is hard to move
A lump that grows fast, has an open sore, bleeds, or appears on its own without a previous wound
You are about to have surgery or an ear piercing and have had keloids before
For an overview of the clinic's scar treatment services, see Treatment for Scars, Acne Pits, and Keloids.
Quick Summary
A keloid spreads beyond the original wound edge and rarely flattens on its own. A hypertrophic scar stays within the wound edge and usually flattens on its own within 1–2 years.
A keloid is not cancer, but a lump that grows fast, has an open sore, or appears on its own with no wound should be examined by a doctor.
The main treatment is triamcinolone injections at 10–40 mg/mL every 4–6 weeks, together with silicone sheets or gel for at least 12 weeks.
If the lump flattens by less than half after 3–4 steroid injections, the doctor may switch to 5-FU mixed with steroid, or add cryotherapy or laser.
Do not cut a keloid out as the only treatment, because it comes back in 45–100% of cases. Additional treatment after surgery is always needed.
People who form keloids easily should avoid ear piercing and tell their doctor every time before surgery.
Frequently Asked Questions About Keloids
What do the early signs of a keloid look like?
The early signs of a keloid are a wound that has closed but is still dark red after 6–8 weeks, starts to feel thick and firm, itches or stings from time to time, and has an edge that gradually extends beyond the original wound line. On the earlobe it often starts as a firm bump 2–3 mm at the piercing that does not go down even after the earring is removed. If keloids run in your family, see a doctor at this stage, because a small, new lump responds to injections better than an old, large one.
How do I make a keloid shrink?
The most effective method is to inject the steroid triamcinolone acetonide 10–40 mg/mL into the lump every 4–6 weeks, usually 3–6 times, together with wearing a silicone sheet 12–24 hours a day for at least 12 weeks. If the lump has flattened by less than half after 3–4 injections, the doctor may switch to 5-FU mixed with steroid, or add cryotherapy or laser. Scar creams or ointments alone usually do not shrink a keloid that has already become a firm lump.
Can lasers treat keloid scars?
Yes, but as an add-on treatment, not the main one. Vascular laser helps reduce redness and itching and softens the scar, while fractional or carbon dioxide laser reshapes the scar surface and lets medicine penetrate deeper. They are usually used together with injections, need several sessions 4–6 weeks apart, and may leave temporary darkening. Using a laser alone to cut out the whole keloid comes back at a high rate, no different from surgery.
Is a keloid dangerous?
A keloid is not cancer and does not turn into cancer, and it does not spread elsewhere. The main problems are itching, pain, tightness, and appearance. However, a lump that appears on its own without a previous wound, grows unusually fast within a few months, has an open sore or bleeding, or does not respond to injections at all should be examined by a dermatologist and may need a biopsy, because some tumours look like a keloid in the early stage.
What causes a keloid on the ear?
Most ear keloids come from an ear or ear cartilage piercing wound, especially when the piercing becomes inflamed, infected, or has a long-lasting reaction to the metal in the earring, in people who are genetically prone to keloids. The treatment that works well for a large lump is surgical removal, followed by steroid injections into the wound every 2–4 weeks and wearing a pressure earring 12–24 hours a day for 6–12 months. People who have had one should not get new ear piercings.
How many days until a scar fades?
A normal scar does not fade in a few days but takes months to years. From 3 weeks to 3 months after the injury is when the scar is reddest and most raised. It then gradually fades and flattens over 3–12 months and settles within 12–24 months. If the scar keeps getting thicker or spreads beyond the original wound edge, it may be a hypertrophic scar or a keloid, and you should see a doctor without waiting for a full year. Starting silicone as soon as the wound closes helps the scar flatten and fade faster.
Read more articles about skin conditions at All Skin Condition Articles.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed 12 October 2026
The information in this article is general knowledge and is not a diagnosis or a personal prescription. The choice of medicine, strength, number of sessions, and treatment method is the doctor's decision after a physical examination. Results vary from person to person. Injections, cryotherapy, lasers, and surgery carry risks and possible side effects, and should always be assessed and performed by a doctor.
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