What are hypertrophic scars?
A hypertrophic scar is a thickened, wide, often raised scar that develops where skin is injured. Scars are common during the wound healing process, but a hypertrophic scar is a result of an abnormal response to a trauma or injury.
In certain people, body cells called myofibroblasts produce too much collagen during healing. This can happen simply as a result of a person’s skin type and healing tendencies. More commonly, overproduction of collagen occurs when a wound is infected or inflamed, under a great deal of tension or motion (such as in injuries over a joint), or left to heal without stitches.
The scars are a frequent complication of burn injuries, but can also form after piercings, cuts, or even acne. Hypertrophic scars are similar to keloid scars but tend to be milder and don’t grow beyond the boundaries of the original skin injury.
The scars aren’t dangerous or life-threatening. They can be itchy and painful, but more often are simply a cosmetic issue. Some people seek treatment to minimize the appearance of the scar. There isn’t an officially established treatment regimen for hypertrophic scars, but a variety of treatments can help get rid of the scar more quickly.
How are hypertrophic scars treated?
Your doctor may recommend one or several of these treatments to help flatten and shrink your scar.
It’s important to remember that it can take a full year for a scar to mature. In that time, your body is remodeling and trying to improve the scar tissue on its own. Most doctors will therefore not treat an early hypertrophic scar. They’ll typically ask you to wait several months to a year before starting any treatment.
Corticosteroid treatments: Corticosteroid injections are considered a first-line treatment for hypertrophic scars. Injecting a steroid into the scar every six weeks may help flatten and soften the scar. There’s a limit to the number of times this can be performed, however, as the steroids may also weaken normal tissue around the scar.
Laser therapy: Laser therapy is more effective in newly formed scars than in older scars. The lasers work by burning and flattening elevated scars. They also target the red and pink pigments in the scars to lighten them.
Bleomycin: Bleomycin is a metabolite of a strain of soil bacteria. It’s shown promising results when injected directly into a hypertrophic scar. It may help improve the scars appearance and relieve itching and pain. More clinical trials are needed to confirm its efficacy.
Cryotherapy: In cryotherapy, a doctor or dermatologist freezes the scar tissue with liquid nitrogen to help flatten it. Cryotherapy has been shown to be successful, safe, nontoxic, and well-tolerated in a number of small studies.
Surgery: After waiting at least a year, a hypertrophic scar can be excised, or cut out, and closed again with stitches. This treatment tries to re-heal the injury while eliminating the issues that may have caused the scar in the first place, such as infection, inflammation, or tension.
Silicone sheets: Silicone elastomer sheets are noninvasive and can be applied as soon the skin heals after an injury. They’re also considered a first-line treatment for hypertrophic scars. Many silicone products are available, including sheets, gels, sprays, and foams. Many are available over the counter (OTC). A sheet must be worn over the scar for 12 to 24 hours per day for 2 to 3 months. You have to apply the gel multiple times per day.
Pressure and massage: One of the cheapest and most effective ways to help heal the scar is to apply pressure and massage to the area. You can use bandages or tape to apply pressure. Over time, it can help weaken the scar tissue and improve the appearance of the scar.
Onion extract creams: Another OTC option is a topical gel made of onion extract. This product is commonly marketed as Mederma. However, limited clinical data shows its effectiveness in reducing the appearance of hypertrophic scars.
Bio Oil: Bio Oil is marketed as a treatment for all different types of scars. It can be purchased at many beauty supply stores. Clinical trials for Bio Oil showed positive results. However, the sample sizes were small. More research is needed to confirm that Bio Oil can effectively reduce the appearance of hypertrophic scars.
Hypertrophic scars vs. keloid scars
Before treating a hypertrophic scar, it’s important to differentiate it from a similar type of scar called a keloid. Keloid scars are smooth, hard, benign growths that also form when scar tissue grows excessively. Even your doctor may have difficulty telling the difference between a hypertrophic scar and a keloid, but it’s important to distinguish them because the treatment may be different.
In general, hypertrophic scars:
- are raised, but rarely more than 4 millimeters above the skin
- are red or pink in color
- can develop anywhere on the body
On the other hand, keloids usually:
- are raised more than 4 millimeters from the skin
- grow beyond the boundaries of the original incision or wound
- are pink to purple in color
- evolve and grow over time
- form on the earlobes, shoulders, cheeks, and chest above the sternum
Both scars tend to occur more commonly in darker skin types. Hypertrophic scars tend to be easier to treat than keloids, which have a high recurrence rate despite treatment.
Preventing hypertrophic scars
In you experience an injury, especially a burn injury, or if you have surgery, there are ways to help prevent hypertrophic scarring. These include:
- cleaning and caring for the wound properly, such as by applying wound dressings to prevent infection
- using silicone sheeting after a surgery
- injecting a corticosteroid after a surgery
One study found that immediately cooling a burn with cold water compresses and applying tea tree oil can help the skin heal better. This treatment may help prevent hypertrophic scars from forming, but more research needs to be done.