Lash serum timeline.

Worked example

Start on 10 October 2026 with 6 mm lashes. In the label's 278-patient trial, the share of Latisse users (n=137) with at least a one-grade gain on the Global Eyelash Assessment was 5% at week 1, 15% at week 4, 50% at week 8, 69% at week 12, 78% at week 16, 79% at week 20, against 2%, 8%, 15%, 20%, 18%, 21% for vehicle. Week 16 is 30 January 2027. The average length gain at week 16 was 1.4 mm, 25 percent, so 6 mm x 1.25 = 7.5 mm is the trial-average estimate.

How it works

Milestone date = start date + weeks x 7 days. The percentages are copied from the label's Table 2: users with at least a 1-grade increase from baseline on the 4-point Global Eyelash Assessment (Latisse n=137, vehicle n=141). The length estimate = current length x 1.25, from the mean gain of 25 percent (1.4 mm) at week 16.

What this is not. This covers prescription Latisse (bimatoprost ophthalmic solution 0.03%), applied once nightly to the upper eyelid margin. Other lash serums are different products with different ingredients, and this tool says nothing about them. The label says that on stopping, eyelash growth is expected to return to its pre-treatment level; effects started to return toward baseline in the 4 weeks after the 16-week treatment. It also warns that bimatoprost can cause increased brown iris pigmentation that is likely to be permanent, and eyelid skin darkening that may be reversible, and people on prostaglandin eye drops for eye pressure should only use it after consulting their physician.

Sources and basis (opened 2026-10-08): AbbVie, LATISSE (bimatoprost ophthalmic solution) 0.03% US Prescribing Information, revised 7/2024. Table 2 (weeks 1, 4, 8, 12, 16, 20), Table 3 (length 1.4 mm, 25%), sections 2, 5.1 to 5.4, 14 and 17.

FAQ

How long does lash serum take to work?

For prescription Latisse, the label trial showed 15 percent of users with at least a one-grade gain on the Global Eyelash Assessment at week 4, 50 percent at week 8, 69 percent at week 12 and 78 percent at week 16. The label does not say anything about other serums.

How long do lash serum results last?

The label says the effect is not permanent: after you stop, eyelash growth is expected to return to its pre-treatment level, gradually. In the trial, effects began returning toward baseline during a 4-week follow-up.

How much longer do lashes get with Latisse?

In the label trial the mean gain at week 16 was 1.4 mm, a 25 percent increase in length, and a 106 percent increase in fullness. Individual results vary.

Is Latisse safe?

It is a prescription eye product. The label warns of possible likely permanent brown iris colour change, eyelid skin darkening and unwanted hair growth where it touches skin, and it should be discussed with a doctor, especially for people on eye-pressure drops.

Does this tool apply to over-the-counter lash serums?

No. These figures come from the Latisse prescribing information for bimatoprost. Cosmetic serums are different products without this data.