Hair Growth Cycle Explained: Anagen, Catagen & Telogen

Written by Lucía Martínez, Head of editorial content · Last updated: August 25, 2026

Understanding the hair growth cycle — anagen, catagen, and telogen — is the single most useful piece of biology any woman dealing with thinning hair can know. Once you understand what is happening inside each follicle, every subsequent decision about nutrition, supplements, and scalp care starts to make far more sense.

What is the hair growth cycle?

Each of the roughly 100,000 follicles on a typical human scalp operates on its own independent clock. Rather than growing continuously, every follicle cycles through a sequence of phases: a long period of active production, a brief transitional window, and a resting interval before the whole process restarts. This cycling behaviour is why you are not completely bald for the weeks it would take a new hair to emerge after shedding — because only a fraction of follicles are resting at any one time.

The three recognised phases are anagen (growth), catagen (regression), and telogen (rest). Some researchers also describe a short fourth phase called exogen, when the old hair fibre is actively shed from the follicle, though it is often grouped within telogen for simplicity. The relative proportion of follicles in each phase at any given moment determines how thick, dense, and long your hair appears.

On a healthy scalp, roughly 85–90% of follicles are in anagen at any one time, around 1–3% are in catagen, and the remaining 10–15% are in telogen. When that ratio shifts — more follicles resting, fewer actively growing — noticeable thinning or increased daily shedding tends to follow.

Anagen: the active growth phase

Anagen is by far the longest phase of the cycle. During anagen, cells in the hair bulb — the rounded base of the follicle that sits deep in the dermis — divide rapidly to produce the keratinised protein fibres we recognise as hair. A single strand typically grows around 1–1.5 cm per month during this phase, although genetics, age, and hormonal status all influence the exact rate.

The duration of anagen is what sets the theoretical ceiling for how long your hair can grow. In scalp hair, anagen generally lasts between two and seven years, with considerable individual variation. Women typically have longer anagen phases than men, which is one of the biological reasons women can more readily grow very long hair. Eyelash and eyebrow follicles, by contrast, have anagen phases of only 30–45 days, which is why those hairs stay short regardless of how carefully you treat them.

Inside the follicle during anagen, the dermal papilla — a cluster of specialised cells at the very base — plays a central role in signalling. It communicates with surrounding stem cells to keep the proliferation programme running. Nutrients including amino acids (the building blocks of keratin), B vitamins, iron, zinc, and biotin all feed into the biochemical machinery that sustains this rapid cell division. A sustained shortfall in any of these can shorten the anagen period prematurely, reducing the window in which each strand can grow.

Catagen and telogen: transition and rest

Catagen: the brief farewell

When a follicle has completed its anagen cycle, it enters catagen: a tightly controlled regression phase lasting approximately two to three weeks. During catagen, cell division in the bulb stops abruptly, the lower section of the follicle shrinks, and the dermal papilla condenses upward toward the skin surface. The hair fibre stops elongating and becomes a “club hair” — anchored at the top of the now-shortened follicle but no longer attached to its nutrient supply.

Catagen is a normal, healthy event. The follicle is not dying; it is preparing to rest and eventually regenerate. Problems arise only when an external trigger forces follicles into catagen before they have completed a full anagen cycle, cutting the growth phase short and leaving fewer active fibres on the scalp at any one moment.

Telogen: rest and renewal

Telogen is the resting phase, lasting roughly two to four months in scalp hair. The club hair sits passively in the follicle while, deeper down, a new anagen hair begins to form. Eventually the emerging new hair physically pushes the club hair out — the exogen event — and the cycle restarts.

Losing 50–100 hairs per day is considered within the normal range for a healthy adult, and nearly all of these shed hairs are telogen club hairs. It is only when the proportion of follicles in telogen rises significantly — a condition called telogen effluvium — that shedding becomes noticeable as clumps on a hairbrush, in the shower drain, or on a pillow.

*Exogen is sometimes classified as a separate fourth phase; it is included here for completeness.

What disrupts the hair growth cycle?

A healthy hair growth cycle depends on a stable internal environment. Several factors are well-documented as disruptors that can shorten anagen, accelerate the move into catagen, or extend telogen:

Hormonal changes

Androgens — particularly dihydrotestosterone (DHT) — can progressively miniaturise susceptible follicles by shortening successive anagen phases. This is the central mechanism in androgenetic alopecia, the most common form of hair thinning in both men and women. Oestrogen, by contrast, is broadly supportive of anagen; its withdrawal during the perimenopause and menopause is one reason many women notice increased shedding from their mid-forties onward. Thyroid hormones also regulate follicle cycling, and both hypo- and hyperthyroidism are associated with diffuse hair thinning.

Psychological and physiological stress

Significant physical stress — major surgery, childbirth, rapid weight loss, or severe illness — can trigger a synchronised shift of a large number of follicles into telogen simultaneously. Because telogen lasts two to four months, the resulting shedding typically becomes visible one to three months after the stressful event, which is why the connection can be difficult to identify. Chronic psychological stress may also influence follicle cycling through neuroendocrine pathways, though the mechanisms in humans are less completely understood than in animal models.

Nutritional deficiencies

Iron deficiency is one of the most frequently identified nutritional contributors to increased hair shedding in premenopausal women, who are at greater risk due to menstrual losses. Low ferritin (stored iron) is associated with telogen effluvium even when haemoglobin remains within the normal range (Trost et al., 2006). Deficiencies in zinc, vitamin D, and certain B vitamins have also been linked to altered follicle cycling, though causation is harder to establish firmly from observational data alone.

Scalp environment

The scalp is skin, and like all skin it functions best when it is clean, well-oxygenated, and free from excess sebum or product build-up. A blocked or inflamed follicular opening can impede healthy cycling and, over time, contribute to miniaturisation. Regular exfoliation and stimulation of scalp circulation form a practical, low-risk adjunct to any internal support strategy. Our Revive + Restore Scalp Scrub is formulated to clear the scalp environment without stripping natural moisture.

How to support each phase with nutrition and scalp care

Because the hair growth cycle is a biological process rather than a switch you can simply flip, “supporting” it means creating the conditions the follicle needs to complete each phase optimally. There is no supplement that can override genetics or a significant hormonal imbalance, but the evidence for nutritional support of follicle function is meaningful.

Nutrients with the most consistent evidence

• Iron and ferritin: Maintaining ferritin above the lower end of the normal range appears important for sustaining anagen. A systematic review of studies in women found a consistent association between low ferritin and telogen effluvium, even when full-blown anaemia was absent.
• Vitamin D: Vitamin D receptors are expressed in the hair follicle, and lower serum levels have been reported in women with diffuse thinning in several observational studies. The UK government already recommends supplementation for most adults through autumn and winter.
• Zinc: Zinc supports the keratin synthesis process and has antiandrogenic properties at the follicle level in preliminary research. Dietary zinc from meat, seeds, and legumes is the preferred source; supplementation is most relevant when intake is low.
• Biotin: Biotin is essential for keratin infrastructure, though deficiency is uncommon in people eating a varied diet. The evidence for supplementation beyond correcting a deficiency is limited (see the limitations section below).
• Amino acids and protein: Keratin is a protein; insufficient dietary protein reduces the substrate available for fibre synthesis during anagen. Women following very low-calorie or restrictive diets are particularly at risk.

Our Lumeyr Women supplement brings these key micronutrients together in a single daily formula designed around the specific nutritional demands of the female hair growth cycle. For a broader look at the evidence for individual nutrients, see our complete guide to hair nutrition vitamins and minerals.

Scalp stimulation and circulation

Physical stimulation of the scalp — through massage or purpose-designed tools — may support dermal papilla signalling by promoting local blood flow and reducing follicular stress markers. A small randomised study published in 2016 found that standardised scalp massage over 24 weeks was associated with increased hair thickness in the participant group, though the sample was limited to Japanese men and larger replicated studies in women are needed. Mechanically, the principle is sound: the dermal papilla is served by a dense capillary network, and optimising perfusion during anagen makes physiological sense.

Limitations of the evidence

It would be misleading to suggest that the science of follicle nutrition is settled. There are genuine constraints worth understanding before investing in any supplement:

• Most human trials are small. Studies on hair growth supplements rarely exceed a few dozen participants, making it difficult to draw population-level conclusions. Effect sizes that appear impressive in a 40-person trial often shrink when larger cohorts are studied.
• Many formulas are combined. Products typically contain multiple active ingredients, which makes it impossible to attribute an outcome to any single nutrient. Isolating the contribution of, say, zinc versus iron versus biotin from a combined supplement study is not feasible.
• Self-reported outcomes are unreliable. Hair count and density are genuinely difficult to measure at home. Many studies rely on participant-reported satisfaction or on standardised photography rather than objective follicle counts, introducing bias.
• Biotin supplementation is frequently oversold. Despite widespread marketing, there is no robust evidence that biotin supplementation improves hair growth in people who are not biotin-deficient. High-dose biotin can also interfere with certain thyroid and cardiac blood tests, which is clinically important to disclose to your GP.
• Genetics set the ceiling. Nutrition and scalp care can help a follicle reach its genetic potential; they cannot override it. If your family history includes significant androgenetic alopecia, a trichologist or dermatologist is the appropriate first port of call.

Frequently asked questions

How long is the anagen phase of the hair growth cycle?

The anagen phase of scalp hair typically lasts between two and seven years, with the duration largely determined by genetics and hormonal status. This phase sets the maximum possible length your hair can reach; a longer anagen means more time for each strand to grow before it enters the catagen transition. Factors such as nutritional deficiencies, hormonal changes, and chronic stress can shorten successive anagen phases over time.

What causes more hairs to enter the telogen phase at the same time?

A synchronised shift of multiple follicles into telogen — known as telogen effluvium — is most commonly triggered by a significant physical or psychological stressor, such as childbirth, major surgery, severe illness, or rapid weight loss. Because the telogen phase lasts two to four months, the resulting increase in shedding typically becomes noticeable one to three months after the triggering event. Nutritional deficiencies, particularly low ferritin, and thyroid dysfunction are other well-documented causes.

Can supplements change how long the hair growth cycle lasts?

Supplements cannot override genetically programmed cycle lengths, but they can help ensure the follicle has the nutritional conditions needed to complete each phase without premature interruption. Correcting a deficiency in iron, vitamin D, or zinc, for example, may help restore a disrupted cycle toward its natural baseline. Supplements work best as support, not as a standalone treatment for significant hair loss.

Is it normal to lose hair every day during the telogen phase?

Yes — losing between 50 and 100 hairs per day is considered within the normal range for a healthy adult scalp. These shed hairs are overwhelmingly telogen club hairs being pushed out as new anagen growth begins underneath. Shedding that consistently exceeds this range, produces visible thinning, or is accompanied by scalp changes such as scaling or redness warrants professional evaluation.

Does scalp massage actually affect the hair growth cycle?

A small randomised controlled study found that standardised daily scalp massage over 24 weeks was associated with increased hair shaft thickness in participants. The proposed mechanism is improved blood flow to the dermal papilla, which services the follicle during anagen. Evidence is preliminary and replication in larger, diverse cohorts — particularly women — is needed, but the practice carries no meaningful risk and fits well within a broader hair care routine.

How do I know which phase my hair is in?

You cannot observe follicle phase directly at home, but some indirect signs exist. Hair that is actively growing and retains its root bulb when pulled (with force) is likely in late anagen or catagen; a shed hair with a small white bulb at the base is typically a telogen club hair. A trichologist can perform a trichoscopy or tug test to provide a more accurate picture of your scalp’s phase distribution.

Sources

1. Trost LB, Bergfeld WF, Calogeras E (2006) — The diagnosis and treatment of iron deficiency and its potential relationship to hair loss, Journal of the American Academy of Dermatology
2. Koyama T et al. (2016) — Standardized scalp massage results in increased hair thickness by inducing stretching forces to dermal papilla cells, ePlasty
3. Almohanna HM et al. (2019) — The role of vitamins and minerals in hair loss: a review, Dermatology and Therapy
4. Rushton DH (2002) — Nutritional factors and hair loss, Clinical and Experimental Dermatology

Lucía Martínez

Head of editorial content — Lumeyr

Lucía leads editorial at Lumeyr. With over eight years writing and editing in wellness, beauty and women’s hair health, she focuses on the intersection of science and daily routine, ensuring every Lumeyr piece explains complex topics clearly and without empty promises.