Eyelashes grow back after they fall out or are removed, following a natural, predetermined biological process. Eyelashes are specialized terminal hairs that serve a mechanical function, primarily to protect the delicate surface of the eye by catching debris and regulating moisture evaporation. Like all hair on the body, each individual lash is programmed to follow a specific cycle of growth, transition, and rest before it is shed and replaced.
The Three Phases of Eyelash Growth
The journey of an eyelash is divided into three distinct phases: anagen, catagen, and telogen. The anagen phase is the period of active growth. During this time, the cells in the hair bulb are rapidly dividing, and the lash is firmly attached to the dermal papilla, which supplies it with the necessary nutrients. This active phase is relatively short for eyelashes, typically lasting between 30 and 45 days, and at any given time, only about 40% of the upper lashes are in this stage.
Next is the catagen phase, which is a brief transitional period that lasts approximately two to three weeks. In this stage, the eyelash growth stops entirely as the hair follicle shrinks and detaches from the blood supply. The lash is now fully formed, and the follicle is preparing to enter its resting state.
The final stage is the telogen phase, a long resting period that can last for 100 days or more before the lash naturally falls out. The fully formed lash rests in the follicle while a new hair begins to grow beneath it, pushing the old one out.
Why Eyelashes Don’t Grow as Long as Head Hair
The reason eyelashes maintain a short, uniform length, unlike the hair on the scalp, is due to the genetically predetermined duration of the anagen phase. Scalp hair remains in the active growing phase for years, often between two to six years, which allows it to achieve significant length. The extended time spent in anagen is why regular haircuts are necessary for head hair.
Eyelash follicles, however, are programmed for an anagen phase that lasts only about one to one and a half months. This short duration imposes a natural, biological limit on how long the lash can grow before the follicle signals the transition to the catagen phase. This limitation ensures the lashes remain the optimal length for their protective function, preventing them from becoming long enough to interfere with vision.
Promoting Eyelash Health and Regeneration
Supporting the natural growth cycle requires gentle care and proper nutrition to prevent premature loss or breakage. Mechanical damage, such as aggressive rubbing, harsh curling, or incomplete makeup removal, can cause lashes to break or be pulled out before they reach the end of the telogen phase. Using old mascara or harsh chemical products can also irritate the delicate hair follicles, which may disrupt the cycle.
A diet rich in specific nutrients is important because hair is built from the inside out. Proteins are the building blocks of hair, and B-vitamins, particularly biotin, support the production of keratin, the primary protein component of the lash structure. Minerals like iron and zinc, along with Omega-3 fatty acids, help maintain the health of the follicle and reduce inflammation.
For individuals seeking to enhance their natural lashes, certain cosmetic treatments are available. Over-the-counter serums often contain peptides and moisturizing agents to condition the lashes and reduce breakage. There are also prescription treatments that work by potentially extending the anagen phase, allowing the lashes to grow longer than they naturally would. Results from these products vary and require consistent application to maintain any gains.