Hair is often treated as a cosmetic concern, but it is a biological system operating on a precise and independent schedule inside each follicle on your scalp. When hair appears to grow slowly, falls out in larger amounts than expected, or seems to stall at a certain length, the explanation almost always traces back to the hair growth cycle and where a particular follicle happens to be within it.
The hair growth cycle is not a single continuous process. It is a sequence of four distinct phases, each serving a biological purpose, each operating on its own timeline, and each influenced by factors ranging from genetics and hormones to nutrition and stress. Understanding how the cycle works does not require a background in biology. What it does require is a willingness to challenge some common assumptions about how hair behaves and why.
This article explains each phase in plain language, addresses what disrupts the cycle, and clarifies what the science actually supports versus what remains individual and variable.
What Is the Hair Growth Cycle?
The hair growth cycle is the repeating biological sequence that every hair follicle on the scalp goes through from the moment a new hair begins forming to the moment the old hair is released and shed. The cycle is continuous, meaning once a follicle completes one cycle, it begins another. There is no permanent end point for a healthy follicle, though the quality and speed of each cycle can diminish with age or under prolonged physiological stress.
Each follicle operates on an independent clock. At any given moment, different follicles across your scalp are in different phases simultaneously. This independence is what makes normal daily shedding possible without the scalp losing all its hair at once, as animals that moult seasonally do. The practical implication is that the hair you see growing on your head today represents a snapshot of thousands of follicles at different points in their individual cycles.
The four phases are anagen, catagen, telogen, and exogen. Some older sources describe only three phases by combining telogen and exogen, but current research supports treating exogen as a biologically distinct event driven by specific signalling between the old hair shaft and the emerging new one beneath it.
What Happens During Each Stage of the Hair Growth Cycle?
Each of the four phases involves different cellular activity inside the follicle, and understanding what occurs in each stage helps explain many observable hair behaviours that are otherwise confusing.
Anagen: The Active Growth Phase
During anagen, cells in the hair matrix located at the base of the follicle divide rapidly and produce new hair fibre. The follicle is deeply embedded in the scalp, connected to blood vessels that supply the nutrients required for cell division. Hair grows approximately 1 to 1.5 centimetres per month during this phase, though this rate varies between individuals. The length of the anagen phase is the primary determinant of how long your hair can grow. A follicle in anagen for two years will produce significantly shorter maximum length than one that stays in anagen for six years.
Catagen: The Transition Phase
During catagen, the follicle receives a signal to stop producing new hair. Cell division in the matrix halts. The follicle shrinks in size and detaches from the dermal papilla, which is the specialised cluster of cells that communicates with and nourishes the follicle. The hair fibre stops growing but remains anchored in the follicle as a structure called a club hair. Catagen is the shortest phase in the cycle, lasting approximately two to three weeks.
Telogen: The Resting Phase
The follicle is inactive during telogen. The club hair sits in place, held in the upper portion of the follicle, while the dermal papilla rests. Beneath the club hair, a new anagen hair may begin forming toward the end of telogen. Hair in the telogen phase is not yet shed. It remains in place until the exogen phase occurs. Approximately 10 to 15 percent of scalp follicles are in telogen at any given moment in a healthy cycle.
Exogen: The Shedding Phase
Exogen describes the active release of the club hair from the follicle. Research suggests this is not simply passive loss but involves specific molecular signals that loosen the anchoring of the club hair. A new hair growing up from below can mechanically assist in pushing the old hair out. Normal daily shedding of 50 to 100 hairs represents follicles completing their exogen phase across the scalp on any given day.
How Long Does Each Stage of the Hair Growth Cycle Actually Last?
The duration of each phase is one of the most frequently misunderstood aspects of the hair growth cycle. Specific numbers are commonly cited, but they represent population averages rather than universal constants.
Anagen lasts between two and seven years for scalp hair in most individuals. Genetics is the primary driver of where within this range a person falls. Someone whose anagen phase consistently runs toward seven years will be able to grow hair to significantly longer lengths than someone whose anagen phase runs closer to two years, regardless of how well they care for their hair. This explains why certain people find it genuinely difficult to grow hair past a certain length even with attentive routines. It is not necessarily a product or routine failure. It may simply reflect a genetically shorter anagen window.
Catagen lasts approximately two to three weeks. This is the shortest phase in the cycle by a considerable margin, which is why it is sometimes overlooked in shorter explanations of the growth process.
Telogen lasts approximately three months on average. During this time, the follicle is dormant and the club hair remains in place. Exogen can overlap with late telogen and early anagen in terms of timing, and the physical release of the hair fibre can take days to weeks.
In terms of visible growth across a three-month window, a follicle in active anagen will produce approximately three to four centimetres of new hair. Hair does not grow faster by optimising the cycle, but protecting the anagen phase from premature interruption supports the best growth possible within a person's genetic range.
What Factors Influence How Long Your Hair Growth Cycle Takes?
While genetics sets the baseline for anagen duration, several other factors can influence how smoothly and consistently the cycle progresses. These factors do not override genetics, but they can either support or disrupt the cycle in meaningful ways.
Hormonal changes are among the most significant influences. During pregnancy, elevated oestrogen levels extend the anagen phase, which is why many people experience noticeably thicker hair during the second and third trimesters. After giving birth, oestrogen levels drop sharply and a large number of follicles that had been held in extended anagen transition into telogen simultaneously. The resulting shedding, which typically begins two to four months postpartum, is known as postpartum telogen effluvium. It is temporary in most cases, though the timeline for recovery varies considerably between individuals.
Nutritional status, particularly iron, protein, zinc, and certain B vitamins, plays a role in supporting the cellular activity required during anagen. Deficiencies do not cause the follicle to stop cycling entirely, but they can affect the quality and rate of growth within the anagen phase. Crash dieting or prolonged caloric restriction can also push a proportion of follicles prematurely into telogen.
Significant physiological or psychological stress, including illness, surgery, or sustained emotional strain, is associated with a phenomenon called telogen effluvium, where a larger than normal percentage of follicles shift into telogen at once. The resulting shedding typically becomes visible two to three months after the triggering event, because telogen itself lasts approximately three months before exogen occurs.
Scalp health influences follicle environment. Chronic inflammation at the follicle level, whether from scalp conditions, product buildup, or mechanical tension, can interfere with normal cycling over time. A scalp that is consistently well-supported in terms of circulation and pH balance is better positioned to allow follicles to complete each phase without unnecessary disruption.
Age gradually shortens the anagen phase and may extend the telogen phase across the scalp. This is one reason why hair tends to become finer and grow more slowly over decades. It is a gradual process rather than a sudden one, and individual variation in how pronounced this effect becomes is considerable.
What Are the Signs That Your Hair Growth Cycle May Be Disrupted?
Not every increase in shedding signals a disruption to the hair growth cycle. The threshold for concern is generally considered to be consistent shedding of more than 100 hairs per day over a sustained period, accompanied by visible changes such as widening of the part line, noticeable thinning at the temples, or overall reduction in density across the scalp.
A single shedding event following a stressful period, illness, or hormonal shift is likely a normal cycle response. The body has adjusted the proportion of follicles moving through telogen, and the shedding is the delayed but predictable consequence. In these cases, the cycle typically self-corrects once the triggering factor resolves, though regrowth may take several months to become visible.
Hair that is consistently short across the scalp despite never being cut may indicate a shorter anagen phase rather than breakage, which is a different structural issue. Breakage tends to produce shorter hairs with tapered or split ends, while follicles completing a short anagen phase produce hairs that fall out with the intact root structure still attached as a club hair.
If shedding is severe, prolonged beyond six months, or accompanied by other physical symptoms, consulting a dermatologist or trichologist is the appropriate next step. These professionals can assess whether the pattern reflects a cycle disruption, a scalp condition, an underlying health factor, or something requiring further investigation.
Common Myths About the Hair Growth Cycle
One of the most persistent myths is that trimming hair makes it grow faster. Trimming addresses the condition of the ends of the hair shaft but has no effect on follicle activity. Growth originates entirely from within the follicle, not from the tip of the strand. Regular trimming is genuinely useful for maintaining hair appearance and preventing split ends from travelling up the shaft, but it does not alter the hair growth cycle in any way.
Another common misconception is that brushing hair 100 strokes per day stimulates growth. Gentle brushing can distribute natural oils and provide mild surface stimulation, but there is no evidence that the 100-strokes rule produces measurable growth benefits. Aggressive brushing, particularly on dry hair, is more likely to cause mechanical breakage than to support healthy cycling.
A third myth is that shedding after washing represents a problem with the scalp or follicles. Hair that was already in the exogen phase and ready to release simply becomes visible during washing because water and movement dislodge it from the scalp. The shedding did not begin during the wash. Spacing out wash days may reduce the number of hairs visibly released at once, but it does not affect the total number shed across the cycle.
Finally, the idea that all hair types follow the same growth rate is not well-supported by research. Growth rate, anagen duration, and follicle density can vary across ethnicities and hair types. For individuals with 4c hair texture, the curl pattern means that actual growth may not be visibly apparent in length at the rate it occurs, because the curl contracts the strand considerably. This does not mean 4c hair grows more slowly in terms of follicle activity, but length retention can be more challenging due to structural characteristics and the care required to prevent mechanical damage over time.
How Does the Australian Climate Affect Your Hair Growth Cycle?
The hair growth cycle itself is not directly altered by climate in a dramatic or rapid way. However, the scalp environment, which influences follicle health and therefore cycle quality, is meaningfully affected by heat, UV exposure, and humidity. These are prominent factors across much of Australia for a significant portion of the year.
High UV exposure accelerates oxidative stress at the scalp surface. While the follicle itself sits below the surface of the skin and is relatively protected from direct radiation, chronic scalp sun exposure can contribute to surface inflammation and changes in the lipid barrier of the scalp. A compromised scalp surface creates a less supportive environment for follicle function over time, particularly during extended periods of outdoor activity.
Heat and humidity increase sweat production, which can alter the pH balance of the scalp and create conditions that favour microbial overgrowth. An overgrown scalp microbiome can contribute to inflammation, which in turn creates a less stable environment for follicles completing their cycles. Regular but gentle cleansing suited to the scalp's needs becomes particularly relevant in warmer and more humid regions and seasons.
Seasonal variation in Australia, while less extreme than in northern hemisphere climates, can still influence the proportion of follicles entering telogen. Some research suggests a mild tendency toward increased telogen activity in late summer, though this is considerably less pronounced than the seasonal moults seen in animals. For most people in Australia, this may manifest as a subtle increase in shedding in autumn that resolves on its own.
The practical implication is that scalp care is not a cosmetic afterthought in the Australian context but a functional part of supporting consistent follicle cycling. Lightweight, breathable formulations that cleanse effectively without stripping the scalp's natural moisture barrier are well-suited to warmer Australian conditions.
What the Hair Growth Cycle Cannot Tell You
The hair growth cycle is a useful framework, but it has clear limits as a predictive or diagnostic tool on its own. Knowing the cycle phases does not allow someone to calculate exactly when regrowth will appear, how long their hair will ultimately grow, or whether a specific product will improve their outcomes. Each of these questions depends on individual biology that the general cycle model does not capture.
The cycle also cannot diagnose androgenetic alopecia, scarring alopecia, or other conditions that involve structural changes to the follicle itself. These conditions require clinical assessment. A knowledge of the cycle provides useful context but should not be used to self-diagnose or to delay professional consultation when changes are significant or prolonged.
Growth timelines are often overestimated by people who have read that anagen can last up to seven years. Not everyone's anagen phase is at the longer end of that range, and expecting dramatic regrowth based on general cycle knowledge can lead to unnecessary product experimentation or frustration. The cycle explains the mechanism. It does not guarantee a specific outcome.
What You Can Practically Do With This Information
Understanding the hair growth cycle is most useful as a framework for setting realistic expectations and making more informed decisions about your routine and product choices. The most evidence-consistent approach to supporting the cycle involves ensuring nutritional adequacy across protein, iron, and key micronutrients, managing stress where possible, and maintaining a clean and well-supported scalp environment.
These actions do not override genetics, but they create conditions in which follicles can complete their cycles without unnecessary interruption. If you are experiencing shedding following a triggering event such as illness, hormonal change, or a period of high stress, knowing that the telogen-to-exogen sequence takes approximately three months from its trigger means that patience is genuinely part of recovery. Regrowth after a shedding event will not be immediately visible. New anagen hairs typically appear as short strands near the scalp two to four months after the cycle restarts, and full recovery of density may take longer depending on the extent of the shedding event.
If you are concerned about hair loss beyond what seems normal, the cycle framework helps you communicate more clearly with a dermatologist or trichologist. Being able to describe the pattern, the timing, and any potential triggering events helps a clinician assess the situation more accurately and efficiently.
Supporting Your Scalp Through the Cycle
Hair Folli's scalp-first formulations are developed with the follicle environment in mind. Gentle, pH-considerate cleansing during the anagen phase and targeted scalp support during recovery periods align with what the biology of the hair growth cycle actually requires, without overcomplicating your routine.
Frequently Asked Questions About the Hair Growth Cycle
How long is a complete hair growth cycle?
A full hair growth cycle from anagen through to exogen varies considerably between individuals. The anagen phase alone can last anywhere from two to seven years. Combined with catagen (two to three weeks) and telogen (approximately three months), one complete cycle for scalp hair can span two to seven years or more depending on genetic factors unique to each person.
How do I know if my hair growth cycle has been disrupted?
Signs of disruption include consistent shedding of more than 100 hairs daily over several weeks, noticeable thinning at the part line or temples, or hair that seems to have stopped growing beyond a previous maximum length. One-off shedding events following illness, stress, or hormonal changes are typically normal cycle responses and usually resolve over several months without intervention.
Does hair grow during the telogen phase?
No. During telogen, the follicle is in a resting state and is not producing new hair fibre. The hair shaft grown during anagen remains in place as a club hair until the exogen phase triggers its release. A new anagen phase may begin before the club hair is shed, which is why short regrowth hairs can sometimes be seen near the scalp before older hairs have fully released.
Why does some hair never seem to grow past a certain length?
Maximum hair length is determined largely by the duration of the anagen phase. If your anagen phase is genetically set to two to three years, hair growth will stop once that period has passed, regardless of length. This is a biological ceiling rather than a product or routine problem. Hair care practices influence the condition of the length achieved, but they cannot significantly extend the anagen phase beyond its genetic range.
Is it normal to shed more hair in summer in Australia?
Some research suggests a mild seasonal pattern in telogen activity, with a slight increase in shedding in late summer in some populations. In Australia, the more practically relevant factor is scalp heat and UV exposure during warmer months, which can affect the scalp environment. Increased visible shedding after time in the heat is more often related to scalp conditions than to a dramatic seasonal cycle shift.
Can I speed up the hair growth cycle?
The overall cycle speed is primarily genetically governed and cannot be significantly accelerated. What is possible is reducing the likelihood of the anagen phase being cut short by disruptions such as nutritional deficiency, scalp inflammation, or physiological stress. Supporting the conditions that allow each phase to proceed naturally gives follicles the best opportunity to operate within their genetic potential.
What does the exogen phase look like?
Exogen hairs are the strands that appear in your brush, on your pillow, or in the shower. A club hair completing exogen will typically show a small, white or pale bulb at the root end. This bulb is the keratinised base of the follicle, not the living follicle itself, so its presence in shed hair is entirely normal and does not indicate follicle damage or permanent hair loss.
Conclusion
The hair growth cycle is the foundational process behind everything observable about hair, from its growth rate to its shed pattern and maximum length potential. Understanding that each of the four phases, anagen, catagen, telogen, and exogen, serves a distinct biological purpose helps make sense of experiences that might otherwise seem alarming or confusing. Shedding is not failure. Short hair is not always breakage. Slow regrowth after a stressful period is not always permanent. The hair growth cycle tends to self-correct when the conditions that support it are in place, and where it does not, professional assessment provides a more reliable path forward than routine changes alone.
Ashly Labadie is a haircare researcher and routine advisor specialising in scalp health, flat hair, and long-term hair performance. She has tested 30+ hair care products available in Australia across different hair types and climates, tracking results over weeks and months rather than after first use. In addition to product testing, Ashly helps individuals build practical haircare routines and choose products based on scalp condition, lifestyle, and long-term goals. She works in collaboration with the Hair Folli Editorial and Research Team to align real-world insights with formulation science and current research, ensuring content remains accurate, realistic, and evidence-informed.