Low-Level Laser Therapy and Hair: What a 2009 Chapter Explains

Where did laser therapy for hair come from?

Lasers have a longer history than you might think. According to the chapter, Albert Einstein laid the groundwork in 1916, and the first working laser came in 1960. The lasers used for things like hair removal and tattoo removal are "hard" lasers that deliver heat, with power measured in watts. Low-level lasers run on milliwatts instead, which is why they're also called "cold" or "soft" lasers.

In 1966, a research group in Budapest reported that low-power laser light could stimulate rat skin, and in 1968 it studied laser light and hair in mice, the chapter says. Later reports looked at people with alopecia areata (1984) and pattern hair loss (1987). Interest in lasers for hair loss grew after 2003.

How is laser light thought to affect hair?

The authors describe several theories:

1. Cell energy. One widely accepted idea centers on the mitochondria, the parts of cells that make energy. Red and near-infrared light is thought to be absorbed by an enzyme there called cytochrome c oxidase. The authors suggest the extra energy this makes (ATP) may play a part in how follicles grow, but they present it as a theory.

2. Blood flow. Another theory the authors describe is that the light may increase blood flow in the scalp.

3. Cell signaling. Light may shift the chemical balance inside cells, the authors write. Cells respond differently depending on their starting state, which may help explain why responses vary.

Dose matters too. The authors note that too little light may have no effect and too much may also have a smaller effect, so the right dose is still an open question.

What research does the chapter describe?

The chapter summarizes two 26-week, placebo-controlled studies of a hand-held laser comb used three times a week: one in 123 men and one in 63 women with pattern hair loss. In the men's study, the authors report that hair counts in the laser group rose by an average of 18.8 hairs per square centimeter, while the placebo group's fell by 10.6. In the women's study, they report an average rise of 17.9 hairs per square centimeter in the laser group and a fall of 9.4 in the placebo group. The chapter's before-and-after photos of five patients are individual cases, not study results.

Both studies tested the same laser comb. The authors note that research on lasers for pattern hair loss was limited when they wrote the chapter.

What this means for you

• Many home devices are sold directly to consumers without published studies, so the authors say clear measures of success are needed.

• The authors also call for long-term studies over years, studies in women and men separately, and research on wavelength and how often sessions should happen.

Beyond the Study: if you're curious about a laser device, talk with a board-certified dermatologist first and ask whether that device has published studies behind it.

FAQs

Is red light the same as a laser? The chapter is about low-power lasers, and most devices it lists use red light between 650 and 670 nm. The authors note that LED light isn't a true laser.

What side effects did the studies report? In the two laser comb studies, 11% of men and 14.7% of women using the laser reported minor effects, such as itching, tingling or mild scalp irritation, according to the chapter.

For the full findings and methods, read the full publication: Low level laser therapy in hair loss.

Read the full publication → Leavitt ML, Perez-Meza D, DiBernardo BE. Low level laser therapy in hair loss. In: DiBernardo BE, Pozner JN, eds. Lasers and Non-Surgical Rejuvenation. Saunders Elsevier; 2009:141–153.

Disclosure: Lead author Dr. Matt Leavitt is a co-founder of Xtressé. The chapter itself doesn't include author disclosures.

This article is for education only and is not medical advice. Talk with your healthcare provider about your own hair and scalp health.