The hair growth cycle explained

What is the hair growth cycle?

Each hair on your body grows, slows down, rests, sheds and eventually restarts. This cycle happens inside the follicle, which is the structure in the skin that produces the hair.¹

Not every follicle is active at the same time. On your legs, underarms or face, some hairs may be growing while others are resting. This is why hair can reappear after treatment, even if the area looked smooth a few days earlier.¹

The body hair life cycle matters because most longer-term hair removal methods work best when hair is actively connected to the follicle. If a hair is resting or shedding, it may not respond in the same way.²

The 3 hair growth phases explained

The 3 hair growth phases are anagen, catagen and telogen. Each phase affects how visible the hair is and how well it may respond to removal.2

• What is the anagen phase of body hair growth?

This is the active growth stage of the hair growth cycle, when the hair is forming and lengthening. During this phase, cells in the hair follicle divide rapidly, pushing the hair shaft upwards and allowing it to grow steadily. The hair is fully attached to the follicle and supported by a strong blood supply, which provides the nutrients needed for growth.²

In terms of timing, this phase can last around 30-45 days for body hair (but much longer for scalp hair, often several years).²³ Because the hair is still firmly connected to the root, the anagen phase of body hair growth is the most effective phase for hair removal treatments like IPL or laser, which rely on targeting the follicle directly.⁴

• What is the catagen phase?

The catagen phase is a short transition stage that marks the end of active growth. At this point, the hair stops growing, and the follicle begins to shrink. It also detaches from its blood supply, meaning the hair is no longer receiving the nutrients needed to grow.²

This phase typically lasts around 2-3 weeks, and only a small percentage of hairs are in this stage at any one time.³ Although the hair remains in place, it is no longer actively developing, which is why hair removal treatments are less effective during this stage.⁴

• What is the telogen phase?

The telogen phase is the resting stage of the hair cycle. During this phase, the follicle is inactive, and no new hair growth takes place.² The existing hair stays in place for a period of time, but eventually it is shed to allow a new hair to begin growing in the next cycle.

This phase typically lasts around 2-4 months, making it much longer than the transition phase. Because the hair is no longer connected to active growth inside the follicle, treatments like IPL or laser are generally less effective at this stage.⁴

The phases of hair growth are continuous. A follicle does not stop forever after one hair sheds; it can begin the cycle again.

Why body hair growth cycles differ from scalp hair

Scalp hair and body hair follow the same basic cycle, but the timing is different. Scalp hair has a much longer anagen phase, often lasting several years.² This allows head hair to grow long.

Body hair has a shorter growth phase. That is why body hair typically reaches a limited length and then seems to stop.³ The body hair growth cycle time also varies by area, which is why underarms, legs, arms, bikini line and facial hair do not always respond at the same pace.

This is especially important when discussing body hair growth in women, because growth patterns can vary widely between individuals. The visibility of body hair and how it responds to removal can be affected by several factors⁵:

• Genetics
• Hormones
• Age
• Skin tone
• Hair colour

How body area affects hair removal results

Different areas of the body have different cycle lengths, densities and hair types. This affects how quickly you see results from long-term hair removal.

• Leg hair: The leg hair growth cycle usually involves a mix of growing and resting hairs at any one time. Legs often respond well to consistent IPL because the treatment area is large and hair is usually easier to see against the skin.⁴
• Underarm hair: The underarm hair growth cycle can feel faster because the hair is often darker, coarser and more noticeable. Underarms may show early visible changes with consistent treatment, but they still need repeated sessions.⁴
• Facial hair: Facial hair can be more hormonally influenced than body hair.⁵ This means results may take longer, especially around the upper lip, chin or jawline.⁴
• Bikini line: Bikini hair is often thicker and denser than arm or leg hair.⁴ It may need careful treatment, spacing, and patience.

Why IPL works best during the growth phase

IPL, or intense pulsed light, works by targeting pigment in the hair and delivering light energy towards the follicle.⁶ This process is most effective when your hair is in the anagen phase because the hair is actively connected to the follicle.⁴

However, because only some hairs are in anagen at any one time,² one session cannot treat every follicle effectively. This is why consistency is key - repeated treatments allow you to target different hairs as they enter the active growth stage.

A device like the Philips Lumea 9900 Pro helps deliver a more guided, expert-inspired at-home experience. Through the Philips Lumea IPL app, its real-time coaching system acts like a personal coach during treatment, providing audio and visual feedback as you go.

It guides you through each pass of the device, helping you move in a controlled way across the skin. The app can indicate where to move next, prompt you to reposition when needed and help identify areas that may need more attention. It also supports correct skin contact and device alignment, including when treating curves and harder-to-reach areas.

How to plan safe and effective body hair removal

Understanding the hair growth cycle helps you choose the right method and manage expectations - so you’re not relying on a last‑minute treatment before a holiday and expecting immediate, long‑lasting results.

• Shaving: Shaving cuts hair at the skin surface. It does not affect the follicle or change the growth cycle. Regrowth may feel blunt, but the hair has not become thicker.¹
• Waxing: Waxing removes hair from the root. Because hairs are in different stages, some regrowth may appear sooner than expected.² Repeated waxing can keep skin smoother for longer than shaving, but it is still temporary.
• IPL: IPL is designed for gradual hair reduction, so results build over time rather than instantly like shaving or waxing. It works best on suitable skin tones and hair colours, and consistent use is key to achieving and maintaining results.

The Philips Lumea 9900 Pro is designed to support a consistent IPL routine over time. After each session, the Philips Lumea IPL app generates a smart treatment report, giving you a clear record of the areas treated and your progress across sessions.

These insights can help you understand how your routine is developing, refine your approach for future treatments and keep track of when your next session is due. By making progress and scheduling easier to follow, the app helps you stay consistent with your IPL treatment plan.

Remember that before any hair removal treatments, always read product instructions carefully, patch test when advised and avoid treating on irritated, broken or sunburnt skin.

Hair growth cycle FAQs

How would you describe the hair growth cycle?

The hair growth cycle is the natural process that each hair follicle follows, moving through repeated stages of growth, transition and rest.² During this cycle, hairs grow, stop growing, and are eventually shed before a new hair begins to form.

Because each follicle operates independently, hair is constantly renewing without all hairs falling out at once.²

Why does hair grow back after IPL?

Hair can grow back because not every follicle is in the active growth stage during one session.² Repeated treatments target more hairs as they move into the growth phase.

Does body hair grow at the same speed everywhere?

No. Legs, underarms, arms, bikini line and facial areas all have different growth patterns, density and hormone sensitivity.⁴

The hair growth cycle explains why long-term body hair removal takes time. Because hairs grows, transitions and rests at different moments, no single treatment can target every follicle perfectly.

By understanding the body hair growth cycle, especially the importance of the anagen phase, you can plan safer and more effective treatments. Whether you shave, wax or use IPL, realistic expectations and consistent timing are what lead to better long-term results.