Lash serum looks like the easiest step in any routine: one quick swipe and you are done. In practice, small details make a big difference. Too much product can drift into your eyes and cause irritation. Too little, or too far from the lashes, and you are mostly conditioning your eyelid. Inconsistent use is the most common reason people give up on a serum before they have given it a fair try.
This guide walks through a clean, repeatable routine, using XXtraLash’s directions (twice daily, along the base of the upper and lower lashes) as the worked example. Always follow the directions on your own product, since they differ between brands. If you have not chosen a serum yet, start with our guide to lash serum types and ingredients or our pillar on prostaglandin-free lash serum.
Key takeaways
- Start with clean hands and clean, dry, makeup-free lash lines.
- Apply one thin stroke at the base of the lashes, on the skin right where lashes meet the lid, never on the waterline or in the eye.
- Follow your product’s own directions. XXtraLash is applied twice daily to the base of the upper and lower lashes. Prescription Latisse is applied once nightly to the upper lid only.
- Consistency matters more than quantity. Using extra product does not speed anything up and makes irritation more likely.
Before you start: read your serum’s directions
Lash serums are not all used the same way, and the differences are worth knowing:
| XXtraLash (prostaglandin-free cosmetic) | Latisse (prescription bimatoprost) | |
|---|---|---|
| How often | Twice daily (morning and evening) | Once nightly [1] |
| Where | Base of the upper and lower lashes | Skin of the upper eyelid margin at the base of the lashes only. Not on the lower lid [1][2] |
| Applicator | Built-in slim precision brush | Single-use sterile applicator, one per eyelid, then discarded [1][2] |
| Contact lenses | Apply with lenses out and let dry fully before reinserting | Remove lenses, reinsert after 15 minutes [1] |
The reason Latisse is limited to the upper lid is related to how prostaglandins behave on skin. Its label warns about hair growth where the solution repeatedly touches skin, and about darkening of eyelid skin, so users are told to blot any excess outside the lash line [1]. Our guide to prostaglandin side effects explains these effects in more detail. Prostaglandin-free cosmetic serums do not carry those drug warnings, which is why some, like XXtraLash, are designed for both upper and lower lashes.
What you need
- Your lash serum
- A gentle eye makeup remover or cleanser
- A clean, lint-free towel or tissue
- A mirror with good light
- Clean hands. The American Academy of Ophthalmology stresses keeping lash product applicators from touching other surfaces to avoid contamination, which can lead to serious eye infections [3].
Step-by-step: applying lash serum (XXtraLash example)
1. Wash your hands
Wash with soap and water and dry thoroughly. Clean hands keep bacteria off the brush and away from your eyes.
2. Cleanse and dry your lash line
Remove all eye makeup, including mascara and liner, with a gentle remover. Then wash your face and pat your lids completely dry. Serum applied over makeup or oily residue tends to smear rather than sit at the lash base. If you wear contact lenses, take them out now. Our guide to lash serum with contact lenses has the full routine.
3. Remove excess from the brush
Pull the brush out of the bottle and wipe it lightly against the neck so it is damp, not dripping. One dip covers one eye.
4. Upper lashes
Look down slightly into the mirror. Starting at the inner corner, draw the brush in one smooth stroke along the base of your upper lashes, right where they meet the skin, like a very thin eyeliner. Do not paint the lashes themselves, and do not go onto the waterline.
5. Lower lashes
Look up slightly. Lightly sweep the brush along the base of your lower lashes, again on the skin just below where the lashes emerge, not on the inner rim. Use a lighter touch here, since the lower lash line is closer to the eye’s surface.
6. Repeat on the other eye
Reload the brush, wipe off the excess, and repeat steps 4 and 5.
7. Let it dry
Give the serum a few minutes to dry before you apply mascara, put contacts in, or go to bed. If a little product gathers at the outer corner, blot it gently with a clean tissue.
8. Close the bottle tightly
Recap right away so the brush does not dry out or pick up dust. Never share your serum: the FDA advises against sharing or swapping any eye cosmetic [4].
9. Repeat morning and evening
For XXtraLash, that means once in the morning before makeup and once at night after you cleanse. Linking each application to a habit you already have, such as brushing your teeth, makes it much easier to stay consistent.
How much serum is enough?
Less than most people expect. You want a thin, barely visible line along the lash base. If you see liquid pooling, running into the crease, or your eyes water right after application, you are using too much.
More product does not mean faster or better results. MedlinePlus notes that applying the prescription lash drug bimatoprost more often than directed does not increase its effect [2]. The same practical logic applies to cosmetics: extra serum mostly ends up where you do not want it, which can mean irritation or wasted product.
Morning and evening routines
Morning
- Wash face and hands.
- Apply serum to upper and lower lash lines.
- Let dry for a few minutes.
- Insert contact lenses, if you wear them.
- Apply mascara and the rest of your makeup.
Evening
- Remove eye makeup gently, without scrubbing.
- Cleanse your face and pat dry.
- Apply serum to upper and lower lash lines.
- Let it dry before your head hits the pillow, so it stays on the lash line and not on the pillowcase.
Common mistakes to avoid
- Applying over mascara or eyeliner. The serum cannot reach the lash base through makeup.
- Painting the lashes instead of the base. The lash line is the target.
- Getting product on the waterline or in the eye. This is the most common cause of stinging.
- Overloading the brush. Wipe it on the bottle neck every time.
- Skipping days. Lashes have a slow natural cycle. Our explainer on how long lash serum takes covers why consistency matters.
- Touching the brush to other surfaces. A contaminated applicator can introduce bacteria into the bottle [3].
- Using it on irritated skin. The FDA advises against using eye cosmetics if the skin around the eye is inflamed or infected [4].
- Rubbing your eyes afterward. Rubbing transfers serum into the eye and is hard on lashes.
If you miss an application
Just pick up with your next scheduled application. There is no need to double up. That is also the advice MedlinePlus gives for the prescription lash drug: skip the missed dose and do not apply extra to make up for it [2].
Can you apply lash serum to your brows?
Many people want to use the same product on their brows. Check your serum’s directions first. We cover what to know in our guide to using lash serum on your eyebrows, listed under related reading below.
Pairing serum with the rest of your lash routine
Serum works best as part of an overall gentle routine. Choose an easy-to-remove mascara, avoid tugging with curlers, and give your lashes breaks from extensions or adhesives. Our guides to mascara habits that break lashes, lash lifts and serum, and everyday lash care have more tips.
When to see an eye doctor
Stop using any lash serum and contact a doctor or eye care professional if you notice:
- Redness, swelling, itching or scaling of the eyelids that does not settle after you stop the product. The FDA advises stopping any eye cosmetic that causes irritation and seeing a doctor if it persists [4].
- Eye pain, discharge or sensitivity to light.
- Blurred or decreased vision. MedlinePlus lists this as a reason to call a doctor right away when using prescription bimatoprost [2].
- Sudden, patchy or significant lash loss. Our pillar on thin or falling eyelashes covers possible causes.
If you have glaucoma, uveitis, a recent eye surgery or another eye condition, talk to your eye doctor before starting any lash serum. The AAO recommends asking an ophthalmologist first in these situations [3]. If you have reactive eyes, read our guide on lash serum for sensitive eyes before you begin.
Try a prostaglandin-free serum made for upper and lower lashes
XXtraLash is a prostaglandin-free eyelash serum that conditions lashes for a longer-looking, fuller-looking lash line. Each 3 mL bottle comes with a slim precision brush for applying right along the base of the upper and lower lashes, twice a day.
Frequently asked questions
Where exactly do you apply lash serum?
On the skin at the base of the lashes, right where the lashes meet the eyelid, like a thin line of eyeliner. Do not apply it to the waterline or into the eye. XXtraLash is applied to the base of both upper and lower lashes. Prescription Latisse is applied to the upper lid only.
How often should you apply lash serum?
Follow your product’s directions. XXtraLash is applied twice daily, morning and evening. Prescription Latisse is applied once nightly.
Should I apply lash serum in the morning or at night?
It depends on the product. For XXtraLash, apply in both the morning and evening. Make sure lashes are clean and makeup-free, and let the serum dry before applying mascara or going to bed.
Can I put mascara on after lash serum?
Yes. Let the serum dry for a few minutes first, then apply mascara as usual. Remove the mascara gently at night before your evening application.
What happens if lash serum gets in my eye?
Rinse your eye with clean water or saline. Mild, brief stinging can happen. If redness, pain or blurry vision continues, contact an eye care professional.
Does applying more lash serum work faster?
No. Using more than directed mainly increases the chance of irritation and wastes product. A thin line at the lash base is enough.
Related reading
- Prostaglandin-Free Lash Serum: What It Means and Why It Matters
- How Long Does Lash Serum Take? The Lash Cycle Explained
- Can You Use Lash Serum With Contact Lenses?
- Lash Serum for Sensitive Eyes: How to Choose and Use One
- What Happens When You Stop Using Lash Serum?
- Can You Use Lash Serum on Your Eyebrows?
Sources
- LATISSE (bimatoprost ophthalmic solution) 0.03% prescribing information. U.S. Food and Drug Administration.
- Bimatoprost Topical. MedlinePlus, U.S. National Library of Medicine.
- What You Should Know About Eyelash Growth Serums. American Academy of Ophthalmology, 2019.
- Eye Cosmetic Safety. U.S. Food and Drug Administration.
