Hypertrophic scars: why they raise, how long they last and treatment options

As the British Association of Dermatologists explains, when a wound heals scar tissue forms, and at first its colour and texture may differ from the surrounding skin before it flattens and fades. It is not uncommon for a scar to become slightly thick and raised, and this is what is called a hypertrophic scar.

The NHS lists it among five types of scar. It is usually raised and firm and does not grow bigger than the original wound, the area may be uncomfortable or difficult to move, and it usually fades and flattens over time. Kingston and Richmond describes hypertrophic scars as red and raised, sometimes painful or itchy, and says they can cause distress through their appearance or itchiness, or because they restrict movement when over a joint.

The two are often confused, and the difference affects what to expect. The British Association of Dermatologists says a keloid is a scar that overgrows and becomes larger than the original wound, can develop after very minor damage such as an acne spot or sometimes without obvious injury, spreads beyond the area of skin damage and may be permanent.

Kingston and Richmond explain that keloid scars are caused by an imbalance in collagen production during healing, and the British Association of Dermatologists describes overproduction of collagen, the skin's structural protein, in keloids. The same sources describe hypertrophic scars as a thickened version of normal healing. The NHS describes fine-line scars as sometimes slightly raised to start, so how raised a scar becomes sits on a spectrum.

The dermatologists list factors that make raised scarring more likely in keloid-prone skin, including burns, acne scars, wounds that become infected or where the skin is significantly tight while healing, and surgical wounds; these point to why wound care, infection control and tension on the wound matter, although the leaflet is describing keloids rather than hypertrophic scars specifically.

The NHS suggests some steps for most scars once the wound is fully healed.

• Massage the scar with a water-based cream, such as aqueous cream or E45, a few times a day for up to 10 minutes each time, only when the wound is fully healed.

• Keep the scar covered in the sun for at least 1 year, with clothing or a dressing, and use sunscreen with a sun protection factor of 30 or more.

• Ask a pharmacist about silicone dressings or gels and creams for massage.

• Consider skin camouflage: special creams and powders colour-matched by a trained professional. A GP can refer you or you can refer yourself online, and the products can be prescribed or bought.

You cannot get rid of a scar, but the NHS says most fade over time without treatment, and that if one is more severe or bothering you a GP may recommend treatments or refer you to a specialist. The aim is to improve how it looks. Depending on the type, options include silicone dressings or gels, steroid injections or cream, cryotherapy, laser therapy and skin camouflage, and a GP can refer you for talking therapy if a scar is affecting your mental health.

Kingston and Richmond says treatment of keloid and hypertrophic scars involves a course of steroid injections to soften and flatten the scar and relieve pain or itching, sometimes with silicone sheet or gel to reduce size or restrict growth, and sometimes cryotherapy and laser. It says early treatment can stop a scar growing. It does not recommend surgery to remove these scars because they are likely to grow back larger.

The British Association of Dermatologists leaflet on intralesional steroid therapy describes the injection: triamcinolone acetonide is injected directly into the scar in clinic, usually without special preparation or a numbing injection, with several injections possible in one area and further sessions at least several weeks apart. It lists side effects including pain, bleeding, infection, thinning and denting of the skin at the injection site, visible small blood vessels and lightening or, rarely, darkening of the skin, and says the risk of the steroid being absorbed into the bloodstream in significant amounts is extremely low. For keloids, the same association notes injections are often repeated monthly for 4 to 6 months, and that there is no evidence that any single treatment is better than another.

The NHS advises seeing a GP if a scar is painful or bothering you, because they may be able to suggest treatments. It advises an urgent GP appointment or NHS 111 if the scar is swollen or painful, feels warm to the touch or has pus coming out, which can point to infection. A scar that keeps growing beyond the wound, or appears after a minor injury, may be a keloid and is worth discussing with a clinician.