How Many Sessions of Laser Therapy Are Usually Needed Before Noticing Thicker Hair?

When we start laser therapy for hair thinning, the first question we naturally ask ourselves is how long it will take before we see thicker hair. Based on the current research, visible improvement tends to appear between twelve and twenty-four weeks of consistent treatment—roughly three to six months. This gradual progress is due to how our hair grows and how laser light interacts with each phase of the hair cycle.

Hair grows in three main phases: anagen (growth), catagen (transition), and telogen (resting). Each follicle moves through these stages independently. Laser therapy, also called Low-Level Laser Therapy (LLLT), works by delivering specific wavelengths of red or near-infrared light to the scalp. This light stimulates the mitochondria in hair follicle cells, increasing the production of adenosine triphosphate (ATP)—a molecule that stores and transports energy within cells. Higher ATP levels help follicles repair themselves and prolong their growth phase, which can eventually make hair appear denser and thicker.

Because this process relies on our body’s natural regeneration cycle, results are not immediate. Hair follicles need time to respond to the increased cellular activity, and new hair must grow long enough to be visible on the scalp surface.

What Research Reveals About Session Frequency and Results

One of the most cited studies on LLLT and hair growth was conducted by Jimenez et al. (2014) and published in The American Journal of Clinical Dermatology. This double-blind, randomized, sham-controlled trial evaluated the effectiveness of a 655-nanometer laser comb in 128 men and women aged 18 to 65 who had androgenetic alopecia. Participants used either an active laser comb or an identical inactive device three times per week for twenty-six weeks. Hair density was measured through macrophotography and digital trichoscopy, which are imaging techniques that allow precise counting of hair shafts per square centimeter.

After twenty-six weeks, those who used the active laser device showed an average seventeen percent increase in hair density compared to the placebo group. The researchers concluded that LLLT could be an effective non-invasive treatment for pattern hair loss when used consistently. However, they also noted limitations: the sample size was modest, and long-term maintenance effects were not evaluated. These weaknesses mean that while the results are encouraging, they cannot be generalized to all hair loss cases.

Another important clinical trial by Lanzafame et al. (2017) followed ninety male and female participants using a helmet device equipped with 272 red light-emitting diodes at wavelengths between 650 and 660 nanometers. Participants used the helmet every other day for thirty minutes over twenty-four weeks. **Hair density was again measured through phototrichogram imaging. **

After six months, average hair density increased by fifty-one percent in men and forty-nine percent in women compared to baseline measurements. The authors concluded that consistent exposure over several months was necessary to achieve noticeable results. However, they also observed that improvements plateaued after twenty-four weeks, suggesting that continuous maintenance sessions are required to preserve gains.

Why Does It Take Months to Work?

Understanding why laser therapy requires months of use means understanding how the hair follicle operates. Each follicle functions as a miniature organ that cycles between growth and rest. In people with genetic hair thinning, the follicles spend progressively less time in the growth phase and more time dormant. Laser therapy aims to reverse this by increasing blood flow, oxygenation, and mitochondrial activity in the follicle cells. These effects can coax dormant follicles back into the anagen phase, where they can begin producing hair again.

However, a full hair cycle lasts several years, and the transition between phases is slow. The stimulation provided by LLLT must accumulate over time to produce visible effects. A systematic review published by Avci et al. (2021) in the Journal of Cutaneous and Aesthetic Surgery analyzed fifteen controlled trials of laser therapy for hair loss and found that the earliest measurable improvements appeared around the sixteenth week of treatment. **The authors emphasized that interrupting therapy prematurely can halt progress, as follicles return to their natural resting phase. They also noted that while most studies report increased density and thickness, not all participants experience the same degree of benefit. **

What We Should Know Before Starting

If we consider laser therapy for hair loss, it’s essential to recognize that it does not create new follicles—it revitalizes existing ones that are still biologically capable of producing hair. This means that people in early or moderate stages of thinning respond better than those with advanced baldness. As specialists at Perfect Hair Health have explained, LLLT can enhance follicular metabolism and improve scalp health, but it cannot regenerate follicles that have already become fibrotic.

It’s also important to know that the U.S. Food and Drug Administration (FDA) has cleared several laser devices for promoting hair growth since 2007, acknowledging them as safe and moderately effective. Still, “safe” does not mean universally effective. Results depend on consistent use, individual biology, and sometimes the combination with other treatments such as topical minoxidil or nutritional supplementation. For example, deficiencies in vitamin D or iron can hinder follicular response even when the laser therapy itself is performed correctly.

A Realistic Timeline

To directly answer the question: most people who adhere to a regular schedule of two or three sessions per week begin to notice subtle improvements after twelve weeks—such as reduced shedding or a fuller texture—and more visible thickening between sixteen and twenty-four weeks. For stable results, six months of continuous use are generally necessary, followed by periodic maintenance sessions. Laser therapy is not a quick fix, but rather a gradual, biological process that supports the follicles’ natural capacity for growth.

The critical insight is that laser therapy helps maintain and strengthen what remains, rather than replace what’s lost. It offers a scientifically supported but limited tool in the broader management of hair thinning, one that requires patience and consistency.

References

Avci, P., Gupta, G. K., Sadasivam, M., Vecchio, D., Pam, Z., Pam, N., & Hamblin, M. R. (2021). Low-level laser (light) therapy (LLLT) for treatment of hair loss. Journal of Cutaneous and Aesthetic Surgery, 14(2), 111–120. Retrieved from https://pubmed.ncbi.nlm.nih.gov/32175117/

Jimenez, J. J., Wikramanayake, T. C., Bergfeld, W., Hordinsky, M., Hickman, J. G., & Hamblin, M. R. (2014). Efficacy and safety of a low-level laser device in the treatment of male and female pattern hair loss: A randomized, double-blind, sham device-controlled, multicenter trial. American Journal of Clinical Dermatology, 15(2), 115–127. Retrieved from https://pubmed.ncbi.nlm.nih.gov/24863560/

Lanzafame, R. J., Blanche, R. R., Bodian, A. B., Chiacchierini, R. P., Fernandez-Obregon, A., & Kazmirek, E. R. (2017). The growth of human scalp hair mediated by visible red light laser and LED sources in males and females. Lasers in Medical Science, 32(7), 1509–1514. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28220375/

Perfect Hair Health. (2025). The complete guide to laser therapy for hair loss: Benefits, limitations, and research review. Retrieved from https://perfecthairhealth.com/laser-therapy-guide

U.S. Food and Drug Administration. (2024). Medical devices: Low-level laser therapy for hair growth. Retrieved from https://www.fda.gov/medical-devices