Anagen Phase: The Active Growth Stage of the Hair Growth Cycle

Quick definition: The anagen phase is the active growth stage of the hair growth cycle. During anagen, cells at the base of the hair follicle divide rapidly and push new hair up through the scalp. On the scalp it typically lasts two to seven years, and at any moment most of your hairs are in anagen.

What is the anagen phase?

Anagen is the first of the main stages of hair growth, followed by catagen (a short transition) and telogen (a resting and shedding stage). Each follicle moves through this hair growth cycle on its own schedule, which is why you don't shed all your hair at once.

In anagen, the follicle is at its largest and most active. The hair bulb sits deep in the dermis, wrapped around a cluster of specialized cells called the dermal papilla. According to the NCBI StatPearls chapter on hair physiology, the bulb surrounds the dermal papilla, which carries nerve fibers and a loop of capillary blood supply. Cleveland Clinic explains that this root area is where growth begins, because it gives the hair the blood supply and nutrients it needs.

Matrix cells around the papilla divide quickly, and as they are pushed upward they harden (keratinize) into the hair shaft you can see and style.

How long does the anagen phase last?

Duration varies by body site and by person. For scalp hair, the answer is measured in years, not weeks.

"Scalp hair stays in this active phase of growth for 2–7 years" — Wikipedia: Hair follicle

Wikipedia notes that this period is genetically determined, and Cleveland Clinic gives the same two-to-seven-year range. Eyebrows, eyelashes, and body hair have much shorter anagen phases, which is why they stay short no matter how long you leave them.

This is also the main reason people have different "terminal lengths." Someone with a long anagen phase can grow hair past the waist; someone with a shorter one may find their hair seems to stop growing around the shoulders. The hair isn't actually stopping, it's simply shedding and restarting before it gets longer.

How much of your hair is in anagen?

Most of it. According to Wikipedia's hair follicle entry, up to 85% of follicles are normally in anagen, with 10–14% in telogen and 1–2% in catagen. StatPearls similarly puts the resting (telogen) share at about 10 to 15% at any given time.

What affects the anagen phase?

Several factors can shorten anagen or push hairs out of it early:

Genetics. Anagen length is largely inherited, which sets your natural maximum length.

Hormones. Hormonal shifts, including those after childbirth, can move many hairs out of anagen at once.

Physical or emotional stress. High fever, major surgery, illness, and crash dieting are well-documented triggers that send a large batch of anagen hairs into telogen early. That pattern is called telogen effluvium and is covered in our telogen glossary entry.

Nutrition. Matrix cells divide very quickly, so the follicle relies on steady nutrition. A review in Dermatology and Therapy notes that micronutrients play an important but not fully understood role in the normal hair follicle cycle. See our note on zinc.

Age. Follicles tend to produce finer, shorter hairs over time as growth phases shorten.

Common misconceptions

"Cutting hair makes it grow faster." Trimming affects the ends, not the follicle. Anagen activity happens below the skin.

"Hair grows forever until it falls out." Every hair has a built-in growth window. When anagen ends, the hair enters catagen, regardless of length.

"Shedding means the follicle is dead." Normal shedding is part of the cycle. A healthy follicle re-enters anagen and starts a new hair.

Anagen in beauty and personal care

Because anagen is where visible length and density come from, much of haircare and scalp care is framed around keeping the scalp environment in good shape during this phase.

Scalp care routines. Gentle cleansing, reducing buildup, and avoiding harsh friction or tight styles help keep the scalp comfortable while hairs are actively growing.

Professional treatments. Dermatologists may assess the ratio of growing to resting hairs using tools such as a trichogram or trichoscopy when someone notices thinning.

Light-based devices. Low-level laser therapy (LLLT) and LED devices have been studied for hair. A 2016 evidence-based review in Lasers in Medical Science by Zarei and colleagues evaluated 21 studies and concluded that FDA-cleared LLLT devices were safe and effective for men and women with pattern hair loss who hadn't responded to or tolerated standard treatments. Those findings apply to the specific devices studied, not to light devices in general. Learn more in our entry on photobiomodulation.

Nutrition and lifestyle. Balanced meals, adequate protein, sleep, and stress management support overall health, which the follicle depends on.

How Reseen fits in

Reseen's scalp tools are designed for a consistent at-home scalp-care ritual. Weave is a handheld light comb with 39 × 660nm red VIPE™ precision light emitters, made for a healthier-looking scalp and fuller-looking hair.

Halo, coming soon, is a wireless cap liner with 256 precision light points (128 × 660nm red and 128 × 460nm blue) and 10- to 15-minute modes for daily care and scalp balance. Both are cosmetic devices intended to support scalp health as part of your routine.

Frequently asked questions

How long is the anagen phase of hair growth?

For scalp hair, anagen typically lasts two to seven years, and the length is largely genetic. Eyebrow, eyelash, and body hair have much shorter anagen phases, which is why that hair stays short.

What are the stages of hair growth?

The main stages are anagen (growth), catagen (transition), and telogen (rest and shedding). Some sources also name exogen as the active shedding step at the end of telogen, after which the follicle returns to anagen.

What percentage of hair is in the anagen phase?

Up to about 85% of scalp follicles are in anagen at any given time. Roughly 10–15% are resting in telogen, and only 1–2% are in catagen.

Can you lengthen the anagen phase?

Anagen length is mostly set by genetics, but illness, stress, hormonal changes, and nutritional gaps can cut it short. If you notice sudden or patchy thinning, see a board-certified dermatologist to find the cause.

Browse every term in the Reseen glossary.

Sources

Physiology, Hair — Hoover E, Alhajj M, Flores JL; StatPearls, NCBI Bookshelf, 2023

Hair follicle — Wikipedia, accessed 2026

Hair Follicle: Function, Structure & Associated Conditions — Cleveland Clinic, accessed 2026

Low level laser therapy and hair regrowth: an evidence-based review — Zarei M, et al.; Lasers in Medical Science, 2016

The Role of Vitamins and Minerals in Hair Loss: A Review — Almohanna HM, et al.; Dermatology and Therapy, 2019

This article is for general education and is not medical advice. Reseen devices are cosmetic devices and are not intended to diagnose, treat, cure, or prevent any disease. If you have a skin or scalp condition, talk to a board-certified dermatologist.