Laser or IPL for Age Spots? What the Physics Actually Predicts

Walk into any consultation for age spot removal and you will likely hear two options within the first five minutes: laser or intense pulsed light, usually shortened to IPL. Both are legitimate, widely studied tools for treating solar lentigines, the flat brown spots that accumulate on sun-exposed skin over decades. But they are not interchangeable, and the differences come down to physics, not brand names.

The shared target: melanin. Solar lentigines form when chronic ultraviolet exposure causes localized clusters of melanocytes to overproduce pigment. That pigment, melanin, absorbs light energy very efficiently across a broad range of wavelengths, roughly 500 to 1100 nanometers. Both lasers and IPL exploit this absorption. The idea, called selective photothermolysis, is to deliver a pulse of light that melanin absorbs faster than surrounding tissue can, heating and fragmenting the pigment while sparing the skin around it. Fragmented pigment is then cleared by the immune system or shed upward as the spot darkens, crusts, and flakes off over one to two weeks.

How lasers do it. A laser emits a single wavelength. For pigment, clinicians typically reach for Q-switched or picosecond devices at 532, 694, 755, or 1064 nanometers. The pulses are extraordinarily short, measured in nanoseconds or picoseconds, which matters because shorter pulses create a photoacoustic effect: the pigment particle heats so fast that it shatters mechanically rather than simply cooking. Shorter wavelengths like 532 nanometers are absorbed strongly by superficial melanin, which makes them efficient for lentigines but also riskier in darker skin, where the epidermis itself contains more competing pigment. Longer wavelengths like 1064 penetrate deeper and are absorbed less by epidermal melanin, which is why they are often preferred for skin of color, though they may need more sessions for shallow spots.

How IPL does it. IPL is not a laser. It is a filtered flashlamp that emits a broad band of wavelengths at once, typically 500 to 1200 nanometers, with cutoff filters that remove the shortest, most aggressive wavelengths. Pulses are far longer, in the millisecond range. That means IPL heats pigment rather than shattering it, a gentler thermal process. The broad spectrum is a feature and a limitation. It allows IPL to address redness and pigment in the same pass, which suits patients with mixed photodamage, meaning brown spots plus background blotchiness and visible capillaries. But the same broadband energy is less selective, so IPL generally requires more sessions, commonly three to five, versus one to three for a Q-switched laser on a discrete lentigo.

Where each tends to win. For a small number of well-defined, dark lentigines on lighter skin, pigment lasers are usually more efficient per session. The spot absorbs the pulse, turns gray-white immediately, darkens over days, then exfoliates. For diffuse photodamage spread across the face, chest, or hands, IPL treats the whole field at once and improves overall tone, not just individual spots. Many clinicians combine approaches over time.

Where each carries risk. The main complication for both is pigmentary, not scarring. Post-inflammatory hyperpigmentation, where the treated area comes back darker before it fades, is the most common problem, and it is substantially more likely in medium to dark skin tones, roughly Fitzpatrick types IV to VI. IPL in particular has a narrower safety margin in darker skin because the epidermis absorbs so much of the broadband energy. Hypopigmentation, a lasting light patch, is less common but harder to correct. This is why a test spot in an inconspicuous area is standard practice, and why device settings matter more than device brand.

One nonnegotiable step first. Any flat brown lesion should be evaluated before it is lasered. Lentigo maligna, an early form of melanoma, can closely mimic a benign age spot, and treating it with light destroys the visual evidence a clinician needs for diagnosis. A dermoscopic exam, and a biopsy if anything looks atypical, should precede energy-based treatment. This is the single most important quality marker to look for in any provider.

What neither device can do. No light-based treatment changes the underlying tendency to form new spots. The melanocytes that produced the lentigo were responding to cumulative ultraviolet damage, and untreated sun exposure will recruit new ones. Studies of both modalities show recurrence and new lesion formation within one to two years when patients skip daily broad-spectrum sunscreen. Treated skin is also temporarily more photosensitive, so strict sun protection for at least four weeks afterward is part of the treatment, not an optional extra.

The bottom line. Lasers are precision tools for discrete spots and are the safer long-wavelength option for darker skin in experienced hands. IPL is a field treatment for widespread, mixed photodamage on lighter skin. The best choice depends on your skin tone, the number and depth of your spots, and honest counseling about session counts and recurrence, not on which machine a practice happens to own.

Related reading: IPL vs. Pigment Lasers for Age Spots: What the Physics Actually Predicts.