Keloid vs. Hypertrophic Scar: How to Tell the Difference

Keloids and hypertrophic scars are both raised scars. According to the American Academy of Dermatology (AAD), a hypertrophic scar does not grow beyond the original wound, while a keloid grows much larger than the wound that caused it. The AAD adds that a hypertrophic scar often becomes less noticeable with time, but a keloid rarely fades without treatment.

This guide summarizes what the AAD, MedlinePlus from the U.S. National Library of Medicine, and published scar reviews say. It is general information, not a diagnosis or medical advice. If you are unsure what kind of scar you have, a board-certified dermatologist can examine it and explain your options.

Keloid and hypertrophic scar at a glance

These are general patterns from the AAD and the Japan Scar Workshop’s 2018 consensus document. The consensus document also notes that many scars have in-between features that make it difficult to say which type they are, which is one more reason to have a clinician look at a scar that concerns you.

What is a keloid?

MedlinePlus defines a keloid as a growth of extra scar tissue that occurs where the skin has healed after an injury. The AAD explains that, in someone with keloid-prone skin, anything that causes skin to scar can cause a keloid, including ear and body piercings, acne, chickenpox, burns, cuts, scrapes, bug bites, tattoos and surgical wounds. According to the AAD, the body produces more collagen than it needs to repair the injured skin, which is why a keloid grows bigger than the wound.

Keloids vary widely. The AAD says a keloid can range from the size of a pimple to larger than a football. On an earlobe it is likely to be a round, solid mass; on a shoulder or the chest it tends to spread out across the skin. While a keloid is growing, it may feel tender or painful, itch or burn. It is often red, pink or slightly darker than the surrounding skin when it first appears. MedlinePlus notes that a keloid exposed to the sun during its first year may tan darker than the skin around it, and the darker color may not go away.

Not everyone who scars will form a keloid. The AAD lists factors that seem to increase the risk: African, Asian or Latin American descent; a family history of keloids (about one-third of people who get keloids have a parent, sibling or child who also gets them); age between 10 and 30, the peak time for keloids to develop; and pregnancy. MedlinePlus likewise notes that keloids often run in families.

What is a hypertrophic scar?

The AAD describes the hypertrophic scar as the other type of raised scar. It appears one to two months after the skin is wounded, and its scar tissue does not grow beyond the wound. With time, the AAD says, a hypertrophic scar often becomes less noticeable. The Japan Scar Workshop consensus describes the same boundary: in general, hypertrophic scars do not grow outside the area of the original wound, whereas keloids grow beyond its border.

Where silicone sheeting fits, according to these sources

Silicone gel sheets are flexible sheets with a self-adhesive side, worn over closed skin. Here is how the sources describe their role:

• AAD: lists silicone gel sheets among the options dermatologists may use for keloids, alongside corticosteroid injections, surgery, pressure earrings or garments, cryosurgery, laser treatment and radiation. It says the sheets may help to flatten a keloid, may be applied to a new keloid or after an injury, and are also included in treatment plans after another treatment, such as keloid surgery, to help keep a keloid from returning. The AAD cautions never to apply a sheet to a scab or open wound.
• MedlinePlus: notes that keloids often do not need treatment. If a keloid bothers you, it lists silicone gel or patches among the options a dermatologist may recommend, and cautions that these treatments, especially surgery, sometimes cause the keloid scar to become larger.
• Japan Scar Workshop consensus: groups gel sheets with fixation tape as a way to rest the scar. It reports that a meta-analysis found silicone gel sheets may be useful for keloids and hypertrophic scars, but because the trials were of poor quality, the finding should be interpreted very cautiously.
• Cochrane review (2023): a systematic review of silicone gel sheeting for keloid scars found only two small trials. The authors concluded that there was not enough evidence to show whether silicone gel sheeting makes any difference in treating keloid scars, and rated the evidence as very low certainty.

Taken together, these sources describe silicone sheeting as one option a dermatologist may include in a scar plan, with limited high-quality evidence behind it. Whether and when to use it on your scar is a decision for your dermatologist or surgeon.

When to see a dermatologist

The AAD and MedlinePlus suggest contacting a dermatologist or other health care provider when:

• a scar left by surgery starts to thicken (the AAD advises contacting a dermatologist right away);
• you develop a keloid and want it removed or reduced in size, or you develop new symptoms;
• a wound on a keloid does not heal.

If you have had a keloid before, or keloids run in your family, the AAD suggests telling your surgeon before a planned surgery, because your surgeon may be able to take precautions.

Not every raised growth is a scar. The AAD notes that another skin condition can look like a keloid and that a dermatologist can perform a skin biopsy to check. The Japan Scar Workshop consensus says a biopsy is essential when a lesion is suspected to be a tumor, for example because it is growing rapidly, since some skin tumors can look similar to keloids and hypertrophic scars.

If your clinician suggests a silicone sheet or patch

Ask which size and outline to use, when to start and how long to wear it each day. Then compare products by their dimensions:

• The Epi-Derm Silicone Gel Patch measures 5 x 6 cm (2 x 2.5 inches) and is sold in pairs. Biodermis says the patches can be cut to size.
• Scar FX 1" x 12" Self-Adhesive Silicone Sheeting and Scar FX 1.5" x 9" Self-Adhesive Silicone Sheeting are straight strips with a self-adhesive side that can be cut to fit.

Rejûvaskin and Biodermis both say the sheet should extend 1/4 inch beyond the scar all the way around. Our silicone scar sheet shapes and sizes guide explains how to measure, How to Use Silicone Scar Sheets compares the makers’ wear and care instructions, and Silicone Scar Sheets vs. Silicone Gel covers the gel format MedlinePlus also mentions. You can also browse the silicone scar sheets collection.

Sources: AAD, Keloid scars: Overview, Signs and symptoms, Causes, Diagnosis and treatment and Self-care; MedlinePlus, Keloids; Ogawa R, et al., Diagnosis and Treatment of Keloids and Hypertrophic Scars—Japan Scar Workshop Consensus Document 2018, Burns & Trauma, 2019; Tian F, et al., Silicone gel sheeting for treating keloid scars, Cochrane Database of Systematic Reviews, 2023; Biodermis Epi-Derm Patch; Rejûvaskin sheet-size FAQ. Reviewed October 27, 2026 for general information and product shopping; not a substitute for advice from your clinician.