Laser hair removal (LHR) uses concentrated light to target and damage hair follicles, offering a long-term solution for unwanted hair. The light energy is absorbed by the pigment, or melanin, in the hair, which converts to heat and disrupts the follicle’s ability to grow new hair. Achieving a significant and lasting reduction in underarm hair growth typically requires a series of treatments. Most people need between six and eight sessions to see optimal results.
The Typical Session Range
The underarm area is generally responsive to laser hair removal, often containing the dark, coarse hair that absorbs the laser light most effectively. While the full range of treatments can span from four to twelve sessions, the majority of individuals find their desired outcome within the six to eight session average.
Underarms are considered a hormonally influenced area, which can sometimes mean they require more sessions than non-hormonal areas like the lower legs. However, the hair in this region is usually dense and dark, making it an excellent target for the laser technology.
The Science Behind Multiple Sessions
Multiple sessions are necessary because hair growth occurs in a cycle with three distinct phases, and the laser is only effective during one of them. The phases are Anagen (active growth), Catagen (transition), and Telogen (resting). At any given time, only a fraction of underarm hair follicles are in the Anagen phase.
The Anagen phase is the only time the hair follicle is actively connected to the blood supply and contains the highest concentration of melanin. The laser targets this melanin, and the heat travels down the hair shaft to damage the follicle’s growth center. Hairs in the Catagen or Telogen phases lack this connection, making the laser treatment ineffective. Therefore, treatments must be spaced out to catch the next batch of hair as it cycles into the Anagen phase.
Key Factors That Affect Your Total
The total number of sessions required can fluctuate based on several individual biological characteristics. Hair color and thickness are primary factors, as the laser works best when there is a high contrast between the hair and the surrounding skin. Dark, coarse hair contains the most melanin, allowing it to absorb the maximum amount of light energy and respond quickly to treatment.
Conversely, fine or light-colored hair, such as blonde or red, contains less melanin and may require more sessions or may not respond at all to traditional lasers. Skin tone also plays a significant role in determining the type of laser used. Individuals with darker skin tones, classified higher on the Fitzpatrick scale, require specific laser wavelengths, such as the Nd:YAG laser, to safely bypass the skin’s pigment.
This specialized approach prevents the laser from targeting the melanin in the skin instead of the hair follicle, which can sometimes necessitate a slightly higher number of sessions to achieve the same level of reduction. Hormonal fluctuations, while less impactful on the underarms than on the face, can occasionally stimulate dormant follicles, potentially adding a session to the overall treatment plan.
The Treatment Timeline and Spacing
The spacing between underarm laser hair removal sessions is carefully timed to align with the hair growth cycle. Treatments are typically scheduled four to eight weeks apart, with many clinics aiming for a four-to-six-week interval early in the process. This interval is designed to ensure that the next group of hair follicles has transitioned into the Anagen phase, making them susceptible to the laser.
Maintaining this consistent schedule is important for maximizing the effectiveness of each session. For a person requiring six sessions spaced six weeks apart, the total time commitment for the initial treatment phase would be approximately seven and a half months. Adhering to the recommended timeline ensures that the laser consistently targets the active growth phase, leading to a more comprehensive reduction in hair.
Long-Term Results and Maintenance
Laser hair removal is accurately described as “permanent hair reduction,” rather than permanent removal, because it significantly reduces the number of growing hairs. Most people experience a 70% to 90% reduction in hair growth after completing their initial series of sessions. The few hairs that may regrow are typically much finer, lighter, and sparser than the original hair.
Even after a successful initial treatment course, occasional maintenance sessions may be needed to sustain the results. Hormonal changes, aging, or other biological factors can sometimes cause a few dormant follicles to become active again. These sessions are usually required only once a year or less frequently, ensuring the underarm area remains smooth with minimal upkeep.