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Scar injection—more precisely, intralesional scar injection—delivers medication directly into raised scar tissue, most commonly a corticosteroid, sometimes combined with 5-fluorouracil (5-FU). It is a prescription medical treatment aimed at softening and flattening hypertrophic scars and keloids, not at erasing a scar completely.
Scar injection targets raised scars: hypertrophic scars, which stay within the boundary of the original wound, and keloids, which keep growing beyond it. These scars commonly follow surgery, burns, acne, piercings, or vaccinations, and often appear on the chest, shoulders, upper back, jawline, and earlobes. Beyond appearance, they can itch, ache, or feel tight—relieving those symptoms is also part of what injection therapy is intended to do.
The treatment can soften and flatten overgrown scar tissue, fade redness, and ease itching, but it does not restore skin to its pre-injury state, and a visible mark usually remains. It is not designed for depressed or pitted scars such as acne scarring—those are generally discussed in terms of lasers, microneedling, or fillers instead. Keloids in particular have a known tendency to recur, so expectations should be set accordingly.
The most commonly injected medication is a corticosteroid, delivered into the scar tissue itself rather than the surrounding skin. Inside the scar, it calms inflammation, suppresses the overactive fibroblasts that keep producing excess collagen, and encourages breakdown of collagen already deposited. Some doctors combine or alternate the steroid with 5-fluorouracil (5-FU), which inhibits fibroblast proliferation; whether and how to combine them is a prescribing decision the doctor makes case by case.
At the visit, the doctor examines the scar, cleans the area, and may apply a topical numbing cream or a cold pack first. Because scar tissue is dense, pushing medication into it produces a distinct stinging, pressure-like ache; the scar may blanch briefly, and there can be pinpoint bleeding. Most people resume normal activities the same day. Softening and flattening develop gradually over weeks, and a course typically involves several sessions spaced weeks apart, on a schedule the doctor sets.
A typical candidate is someone with a clearly raised, firm scar—often red, itchy, or tender—that has persisted rather than faded on its own. A worthwhile consultation should cover what kind of scar it is and how it formed, what treatments have been tried and how the scar responded, how much flattening is realistic, whether to combine injections with silicone products, pressure therapy, laser treatment, or surgical excision followed by injections for larger keloids, and the likelihood of recurrence.
Scar injection is not appropriate for everyone. Fresh, still-healing wounds call for standard wound care first, and depressed scars will not improve with this approach. Active skin infection at the site is a reason to postpone. Tell the doctor about pregnancy or breastfeeding, allergies to the medications involved, diabetes, immune conditions, and any other health issues—these are prescription drugs, and whether they are suitable for you is a medical judgment that has to be made in person.
The injection itself is often the most uncomfortable part: a strong, pressured sting as medication enters dense scar tissue. Afterward the area may be red, swollen, bruised, or tender for a few days, which rarely interferes with daily life. Change arrives slowly—the scar softens and settles over weeks rather than days—so follow-up visits are part of the process, and it is normal for the doctor to reassess the response before deciding whether to continue.
Less common effects include thinning (atrophy) of the skin or the fat beneath it, which can leave a dent; lightening of skin color, more noticeable on deeper skin tones; and small visible blood vessels near the injection site. When 5-FU is used, ulceration or darkening at the site can occur. Because these are prescription drugs delivered into living tissue, treatment belongs in a licensed medical institution with a qualified physician—not a beauty salon. Recurrence of keloids after treatment is also well recognized.
Contact the treating doctor if pain keeps worsening, the site develops pus, an ulcer that will not heal, or a noticeable depression, or if the scar rebounds and grows quickly once treatment stops; unexpected changes in the months after injection are also worth reporting rather than watching alone. This article is general information only—it cannot replace the evaluation, diagnosis, or treatment plan of a physician who has examined your scar in person.