Acne Intralesional Injections: Actually, It's the Same Principle as Reducing Burn Scars

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Understanding Acne — 1.1 Folliculitis vs. Acne

The Turning Point for Scarring — 2.1 Scar Risk by Size and Type

How to Stop It Now — 3.1 The Importance of Drainage

Caring for Remaining Marks — 4.1 PIH, PIE, Atrophic, and Hypertrophic Scars

When large, painful acne lesions like nodules or cysts appear, you might be recommended an "acne injection" (intralesional steroid injection). However, many people hesitate at the word "steroid," worrying about potential side effects or fearing they will have to keep getting them once they start. Actually, these injections work on the exact same principle as quickly calming inflammation to minimize burn scars. Rather than "causing" scars, it is a highly effective, direct approach to "preventing" them.

When large, painful acne lesions like nodules or cysts appear, you might be recommended an "acne injection" (intralesional steroid injection). However, many people hesitate at the word "steroid," worrying about potential side effects or fearing they will have to keep getting them once they start. Actually, these injections work on the exact same principle as quickly calming inflammation to minimize burn scars. Rather than "causing" scars, it is a highly effective, direct approach to "preventing" them.

The Idea That "Nodules Will Just Go Away on Their Own" Causes the Worst Scarring

It is very common to wait out a hard, swollen nodule, thinking it will subside in a few days. However, while the nodule remains active, the collagen in your dermis is undergoing continuous damage. If left for over a week, a brown hyperpigmentation mark can persist in that spot for more than a month. If it goes past two weeks, a shallow indentation begins to form.

The advice "leave it alone and it won't scar" only applies to the comedone and papule stages. For nodules and cysts, simply "leaving them alone" is actually the most common path to permanent scarring.

Acne Injections Are Different from Systemic Steroids

The acne injection* used for deep nodules is a procedure where a very small amount of active medication, triamcinolone, is delivered "strictly within the lesion." It is the most commonly used corticosteroid approved by the MFDS (Ministry of Food and Drug Safety), and the amount administered per nodule is only about 0.05 to 0.1 mL.

Why is this important? Unlike oral steroids or intravenous injections, even though it shares the "steroid" name, it barely enters systemic circulation. Systemic side effects like adrenal suppression*, weakened immunity, or weight gain are clinically negligible. The medication acts solely in that one target nodule.

* Acne Injection (Intralesional steroid injection): A procedure where a diluted corticosteroid like triamcinolone is injected strictly within a nodule or cyst in tiny amounts (0.05 to 0.1 mL). It effectively relieves swelling and pain within 24 to 48 hours.

* Adrenal Suppression: A side effect where the adrenal glands produce fewer of their own hormones due to long-term systemic steroid use. Because localized, low-dose injections rarely reach systemic levels, this side effect is clinically unseen in this context.

It Works on the Same Principle as Reducing Burn Scars

In burn medicine, the key variable that determines "how severe the scarring will be" is the "depth of the inflammation." The deeper the inflammation, the larger the area of collagen damage, which solidifies into the size of the final scar. Therefore, for deep burns, a prompt treatment flow utilizing corticosteroid injections, silicone gel sheets, and pressure therapy within the first few days is standard. When inflammation is deep, rapid intervention is the deciding factor in minimizing scars.

It is exactly the same principle with acne nodules and cysts. If deep inflammation is left untreated, collagen damage progresses rapidly within a matter of days. Whether a nodule is resolved in 3 days versus 10 days makes a massive difference in the eventual scar size. The acne injection is the fastest tool to bridge those crucial days, making it a highly reliable way to "prevent" scarring.

Side Effects Are Localized; Concentration is Key

While systemic side effects are virtually non-existent, local side effects can occur if the concentration is too high or the frequency is incorrect. The most common issues are localized skin indentation (atrophy) and temporary loss of pigment (hypopigmentation). Both typically happen when a high concentration (e.g., undiluted 40 mg/mL) is used, or when injections are repeated in the same spot within a 4-week window.

The Korean Dermatological Association’s clinical guidelines emphasize the same principle. It is standard practice to dilute the medication to a safe concentration between 2.5 and 5 mg/mL. The treatment interval is not rigidly restricted; in urgent cases, an extra touch-up can be administered within a few days. However, as long as the injections are not repeated too frequently in the exact same spot, indentation is rarely seen in clinical practice.

When to Treat Once, and When to Repeat

The vast majority of nodules and cysts shrink significantly within 24 to 48 hours of a single injection. If the exact same spot swells up again, we do not enforce a strict waiting period and can provide another injection if needed. Urgent nodules and cysts can receive additional treatment within a few days. However, it is rare to exceed 3 injections within a single treatment cycle.

If multiple nodules continually break out across your face, acne injections alone have their limits. In these cases, we look into systemic treatments such as oral antibiotics or isotretinoin. If you feel like you "constantly need injections," it is a sign that your skin requires a different line of treatment rather than just more injections.

Here is a summary of recommended timing for different scenarios:

The common fear surrounding