Does Red Light Therapy Trigger Acne or Skin Purging?

John J. Schmidt, MD

John J. Schmidt, MD, FAAD, FEADV, is a veteran board-certified dermatologist with 45 years of clinical experience. He remains an actively licensed Colorado physician and continues to teach and train dermatologists internationally. He is board-certified in both Internal Medicine and Dermatology and holds Fellow status with both the American Academy of Dermatology and the European Academy of Dermatology and Venereology. In addition to his dermatology background, he continues to practice part-time Aviation Medicine as an FAA-designated Senior Aviation Medical Examiner. His decades of clinical practice, teaching, and medical leadership bring a deeply experienced perspective to dermatology, skin health, and evidence-based consumer education.

MD Dermatologist FAAD FEADV

When people who have acne start red light therapy, they sometimes notice their acne condition flare, blaming “purging” caused by the red light. They accept this as an explanation because this term is commonly used by the skin care industry. However, it is worth asking whether this word actually applies here for red light therapy by examining the actual mechanism behind it.

Young woman with wavy hair touching her cheek, examining acne blemishes in a mirror.

What Skin Purging Actually Means in Dermatology

Purging is a colloquial term, not a medical one. There is no formal dermatological definition, and the phenomenon as such has not been studied directly.

What the literature does describe is microcomedone formation in acne, the earliest invisible stage of a blocked follicle, sitting just below the skin surface. Agents that speed up epidermal turnover can push microcomedones to the surface faster. Instead of creating new acne, they transform microcomedones into visible active acne lesions sooner. The result looks like a sudden flare, but is composed of lesions that were already on their way.

An explanation with real evidence is retinoid-induced flaring. Both topical and oral retinoids work by regulating epidermal cell proliferation and shedding. Controlled studies have shown a temporary worsening in a subset of users during the first couple of weeks of starting retinoids. So in this case, the retinoids have accelerated mature lesion development, not the creation of new microcomedones. [1][2]

Is Red Light Therapy Known to Accelerate Skin Cell Turnover?

Normal epidermal turnover is approximately 28 days, which is why purging is described as lasting a few weeks rather than months. Red light therapy is not in the category of agents known to accelerate epidermal turnover. That category consists of retinoids and exfoliating acids.

There has been laboratory work done on red light and keratinocytes. One recent study found that red light activates AMPK-dependent fatty acid oxidation that enhances keratinocyte proliferation in cultured cells. However, cultured keratinocyte proliferation cannot be directly correlated to accelerated shedding in living skin, nor to a purging mechanism. [3]

Is red light known to have any influence on acne?

Yes, red light has actually been shown to benefit acne. It targets porphyrins produced by C. acnes bacteria that normally live in the skin follicle, which contribute to the acne inflammatory process. Red light triggers a photochemical reaction on the porphyrins, leading to C.Acnes destruction, thereby reducing inflammation. [4] [5]

In addition, red light has been shown to have yet another direct anti-inflammatory effect in acne by downgrading inflammatory cytokines. [5] While red light has been repeatedly shown to offer benefit in acne, it is still not recommended or approved as a single primary treatment for this condition.

Common Reasons Breakouts Appear After Starting Light Therapy

Something else is usually responsible. Four candidates are worth checking before reaching for the purging explanation.

Acne mechanica. A well-established condition. Wearable LED masks press on the face. Friction, pressure, heat, and surface sebum become trapped on the skin surface. This can lead to irritation of existing microcomedones and new microcomedone formation. The giveaway is the pattern: new acne lesions appear where the device makes skin contact and nowhere else. [6]
Products used around sessions. People often start red light therapy and a new serum or moisturizer in the same fortnight, then falsely attribute the flare solely to the light.
Coincidence. Acne fluctuates on its own. Starting anything new during a flare creates a false association.

How Skincare Products and Device Hygiene Can Affect the Skin

Clean, dry skin is the simplest starting point for use of most at-home LED devices. It is important to remove makeup, sunscreen, and heavy skincare creams prior to LED use, unless the manufacturer specifically directs you to use a product with the device.

Some topical preparations might contain photoallergic or phototoxic ingredients. Applying such immediately before a session might result in redness and/or stinging. In addition, the thickness of the topical preparation may diminish the depth of the red light penetration. If you use prescription skincare, it is recommended to first check with your prescriber whether there might be a light-medication contraindication.

Good hygiene is what most people neglect. Masks and handheld devices that sit against the skin collect sebum, sweat and product residue. They need proper wiping down between uses. Any devices shared between people need thorough cleaning between users.

How to Adjust Treatment Session Length, Frequency, and use of additional products

Session length is one of the most common questions in red light therapy, and one of the most frequently answered incorrectly. How long a session should run depends on the device's irradiance and your physical distance from the panel. This is why copying someone else's treatment routine is often inappropriate. The BestQool brand publishes precise guidance for use of their panels. Only these guidelines should be followed when using their equipment.[7]

Longer treatment time is not necessarily better. Light therapy follows a biphasic dose-response, which means that doubling your session time does not double your results. Past a certain point, more light stops adding benefit and can actually lead to a diminished benefit. [8]

Frequency is also often misunderstood. There is no published evidence that daily sessions work better than three to five times a week.

When also using topical products, it is best to change one variable at a time. If you start using a light device and a new serum at the same time, the results may be confusing. Use the light device alone for a few weeks before adding the use of a topical preparation to your regimen. If breakouts appeared with a mask-style device, then try using a panel that does not touch the skin and observe whether the pattern changes.

When a Breakout May Be Irritation Rather Than a Temporary Acne Flare

The question worth answering is whether you are looking at an acne flare-up or at a skin irritation. A few considerations can help you determine what may be happening.

Location. Acne flares usually tend to occur where you normally break out. On the other hand, irritation tends to occur in different areas, such as where a device contacts the skin.
Character. Stinging, burning, itching, redness, or scaling usually points to irritation rather than a temporary acne flare.
Timeline. Something that keeps worsening or continuing past a few weeks, is not a temporary flare.
Pattern over time. Spots that surface and clear at their usual pace are behaving normally. Irritation tends to linger and keeps returning while whatever is causing it stays in the routine.

As a rule of thumb, if acne breakouts appear where you typically flare and settle within a few weeks, the routine is probably worth persisting with. If they appear in new areas, feel more inflamed, or linger without improving, that points to an adverse reaction worth evaluating.

References：

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Herrera MA, Caldeira da Silva CC, Von Dentz M, Baptista MS, Kowaltowski AJ. Mitochondrial fatty acid oxidation is stimulated by red light irradiation. FEBS Lett. 2026 Jan;600(1):20-38. doi: 10.1002/1873-3468.70195. Epub 2025 Oct 18. PMID: 41108719; PMCID: PMC12793707.
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