Lash Growth Cycle

Understanding the lash growth cycle is one of the most important pieces of knowledge I share with every artist I train, and it's equally important for clients to understand. I have been a working lash artist since 2009 and have run Lash Affair since 2014, and in that time I can tell you that most retention complaints and fill timing confusion come down to one thing: not understanding how natural lashes grow, rest, and shed on their own timeline.

The Three Phases of Lash Growth

Every natural lash on your client's lash line is in one of three growth phases at any given time. Unlike scalp hair, which cycles over years, eyelashes complete their entire growth, transition, and resting cycle in about three to four months. This rapid timeline is why lash extensions are temporary by nature and why fills are a regular part of the maintenance cycle.

A Quick Myth-Buster: How Many Lashes Are Actually Growing?

You may see sources online claiming that 80 to 90 percent of your lashes are in the growth phase at any one time. This is a common misconception, as that figure actually applies to scalp hair. For eyelashes, the number is closer to 40 percent on the upper lash line and around 15 percent on the lower lash line. Understanding this distinction is key to setting realistic expectations for lash fullness and the necessity of regular fills.

Phase 1: Anagen (Active Growth)

The anagen phase lasts approximately 30 to 45 days and is when the lash is actively growing from the follicle. At any given time, roughly 40 percent of your upper lashes and 15 percent of your lower lashes are in this active growth phase, which is why a full set of extensions can be applied at any appointment. There are always healthy, growing lashes to work with.

During this phase, the lash is firmly rooted and at its healthiest, making it the ideal lash to attach an extension to. Extensions applied to anagen-phase lashes will have the longest wear time because the natural lash is not going anywhere soon.

In my training courses, I teach artists to identify anagen lashes by their thickness and positioning. They are usually the most robust lashes on the lash line. Prioritizing these lashes during application improves overall retention for the client.

A healthy eyelash in the anagen phase grows at a rate of about 0.12 to 0.14 millimeters per day. That seems small on paper, but it is exactly why clients notice their extensions have grown out from the lash line by the time they come in for a fill. The base of the extension has moved with the natural lash as it grew.

Phase 2: Catagen (Transition)

The catagen phase is a short transition period lasting about two to three weeks. During this phase, the lash stops growing and the follicle begins to shrink. The lash is still attached, but it is no longer being actively nourished by the follicle. Extensions on catagen lashes will still hold, but they are closer to the end of their natural wear cycle.

I think of catagen lashes as being on borrowed time. They are stable enough to wear an extension, but they will shed sooner than an anagen lash. This is completely normal and part of why clients notice some extensions falling out before others. Those were likely on catagen-phase lashes at the time of application.

Phase 3: Telogen (Resting and Shedding)

The telogen phase lasts up to 100 days. During this time, the fully-grown lash sits dormant in the follicle while a new anagen lash begins forming beneath it. This is a crucial part of the renewal process. Eventually, the new growing lash pushes the old telogen lash out, causing it to shed naturally. This is the natural lash loss that clients sometimes mistake for poor retention.

I always explain to my clients that losing one to five natural lashes per day is completely normal. That is the telogen cycle doing its job. When an extension falls out with a natural lash still attached to it, that is not a retention failure. That is biology. A shed extension with a clean white root attached is actually a sign the application was done correctly. The bond held for the full life of the natural lash, which is the goal.

The Lash Cycle at a Glance

• Anagen (Growth): Lasts 30 to 45 days. The lash is actively growing and ideal for extension application.
• Catagen (Transition): Lasts 2 to 3 weeks. Growth stops and the follicle shrinks. Extensions are still serviceable but closer to shedding.
• Telogen (Resting): Lasts up to 100 days. The lash is dormant and will eventually be pushed out by a new anagen lash. This is when natural shedding occurs.

Seasonal Shedding Patterns

One of the most common questions I get from both artists and clients is why retention seems to drop during certain times of year. The answer is seasonal shedding. Most people experience heavier lash shedding in the spring and fall as their body adjusts to changing daylight hours and temperature. This is similar to how many animals shed their coats seasonally.

During peak shedding seasons, clients may lose more extensions faster than usual. I prepare my clients for this by explaining it during their initial consultation and recommending slightly shorter fill intervals during spring and fall. This proactive communication prevents frustration and builds trust because the client understands what is happening before it starts.

How the Growth Cycle Affects Fill Timing

The standard fill recommendation of two to three weeks is based directly on the lash growth cycle. Within that window, enough lashes have cycled through catagen and telogen that the set needs refreshing, while enough anagen lashes remain to maintain a full appearance. Waiting longer than three weeks typically means too many lashes have shed naturally, and the remaining set may need a full removal and reapplication rather than a fill.

I recommend artists educate clients about the growth cycle at their very first appointment. When clients understand that their natural lashes are constantly cycling and that extension loss is biology rather than a quality issue, they become better long-term clients who maintain realistic expectations and consistent fill schedules.

Factors That Influence the Growth Cycle

Several internal and external factors can speed up or slow down the lash growth cycle. Understanding them is the difference between guessing at retention and diagnosing it.

• Hormones: Changes from pregnancy, menopause, or thyroid conditions can dramatically affect growth and shedding rates.
• Diet and Nutrition: A diet lacking in key nutrients like biotin, iron, and vitamins B and C can weaken lashes and shorten the anagen phase.
• Stress: High cortisol levels can prematurely push lashes from the telogen phase into shedding, leading to noticeably faster lash loss.
• Medications: Certain medications interfere with lash growth cycles, including chemotherapy drugs and some acne treatments.
• Physical Damage: Habitual rubbing, pulling at the lashes, or improper extension removal can traumatize the follicle, disrupting the cycle and sometimes leading to permanent loss.

I have had clients whose retention changed overnight after starting a new medication, and understanding the growth cycle helped us identify the cause quickly. This is why a thorough consultation matters as much as the application itself.

What About Lash Growth Serums?

Clients often ask if lash growth serums really work, and the answer lies in this cycle. Most effective serums use ingredients like peptides or prostaglandin analogues to extend the anagen phase by keeping the lash in its active growth stage for longer than the typical 30 to 45 days. The lash can grow longer and thicker before it transitions to the catagen phase. This is also why it takes several weeks to see results. The serum needs time to influence lashes that are currently in or just entering the anagen phase.

If you are pairing a serum with extensions, apply it to the skin at the lash line rather than coating the extensions themselves. Oil-based formulas can weaken the adhesive bond, so verify the serum is safe for extension wearers before recommending it to clients.

Why This Matters for Your Practice

At Lash Affair, I built our training curriculum around this foundational biology because I believe every artist should be able to explain the growth cycle confidently to their clients. It is the difference between being a technician and being a trusted professional. When you can answer "why are my extensions shedding faster than my friend's?" with the actual biology behind it, retention conversations stop being defensive and start being educational. That is what keeps clients on a consistent fill schedule for years, not months.