How long eyelash extensions can last will depend on an individual's natural lash cycle. All human eyelashes go through a three part cycle during their growth and development.
1. Anagen: The first stage of the eyelash cycle is known as the growth phase. At this part of the cycle, the lashes can last between 30 and 45 days. Approximately 40 percent of our upper lashes and 15 percent of our lower lashes are in the anagen stage at any given time.
2. Catagen: this is the transition phase. Once the lashes in the anagen phase reach their designated length, they stop growing and the hair follicle shrinks. If a lash should fall out during this phase, it won't begin to grow back until the catagen phase has run its course.
3. Telogen is the resting phase where the eyelashes rest before they fall out and a new lash blooms takes its place.
A full life cycle for one lash is generally 4-6 weeks. When eyelashes are applied some eyelashes will be babies, some in the anagen state and some fully grown with only days left in it's cycle. That is why a client will most likely feel that they need a fill of extensions by week 3 or 4 as some of their own natural lashes would have fallen out due to the end of the cycle.
The aftercare will also play a major role in the lifespan of the extensions. Please see our aftercare article for more information.