Can You Use Lash Serum With Your DIY Lash Extensions? An Australian Guide

Short answer: Yes - but only if your lash serum is oil-free and free from prostaglandin analogues. Most aren't. Here's exactly how to use a lash serum without wrecking your DIY lash extensions, which ingredients to avoid, and the routine that keeps your natural lashes thriving underneath.

The short answer: yes, if your serum passes two tests

You can absolutely use a lash growth serum while wearing DIY lash extensions. In fact, it's one of the smartest things you can do — because the better the natural lash underneath, the better the extension grips, lays and lasts.

But there's a catch. Most lash serums on the Australian market fail one (or both) of two tests:

• They contain oil, which dissolves the lash adhesive and shortens your wear time.
• They contain prostaglandin analogues, which can darken iris colour, irritate eyes and cause dark eyelid pigmentation.

If your serum fails either test, it doesn't matter how good your DIY application is — your extensions will lift early, you'll be re-applying every few days, and your eyes may not love you for it.

The Underlash Lash Serum was designed by an Australian DIY-lash-wearer (hi, Laura 👋) for exactly this reason: it's the serum we wished existed when we were wearing our own Quickies and OG Underlash Bond & Seal lashes daily.

Why most lash serums quietly ruin lash extensions

If you've ever had extensions fall out faster than expected and blamed the glue, the climate, or "just your lashes" — there's a strong chance the real culprit is what's sitting on your lash line every morning.

Reason 1: Oil is the enemy of lash adhesive

The bond in any DIY lash extension system — including Underlash's Bond Duo and the pre-bonded strip on The Quickies — is a cyanoacrylate-based adhesive. Cyanoacrylates break down in the presence of oil. Even tiny amounts, applied daily, will:

• Soften the bond at the lash root
• Cause clusters to lift from the outer corners first
• Shorten wear time from a comfortable 10 days down to 2 or 3
• Leave you re-applying The Seal constantly to compensate

Oil-containing ingredients to watch for on serum labels include argan oil, castor oil, jojoba oil, coconut oil, almond oil, mineral oil, and any "nourishing" botanical extracts in an oil base. If "oil" appears anywhere in the ingredient list, assume it'll affect your extensions.

Reason 2: Prostaglandin analogues — the ingredient you've probably never heard of

This is the one nobody talks about, and it's the bigger health concern.

Prostaglandin analogues (PGAs) are the active ingredient in a lot of the "miracle" lash serums on the market. You'll see them on labels as:

• Bimatoprost
• Isopropyl cloprostenate
• Dechloro dihydroxy difluoro ethylcloprostenolamide
• Methylamido dihydro noralfaprostal

They're effective at making lashes grow — they were originally developed as glaucoma medication, and the side effect of longer lashes is what kicked off the whole lash serum category in the first place. But they come with documented side effects that include:

• Permanent darkening of the iris (especially in people with hazel or light brown eyes)
• Darkening of the eyelid skin
• Sunken, hollow-looking eyes from fat loss around the eye area
• Red, itchy, irritated eyes
• Drooping eyelids

The Underlash Lash Serum deliberately contains zero prostaglandin analogues. It uses peptides, biotin and panthenol to support the natural lash growth cycle — so you get genuinely stronger natural lashes without the eye-colour-change roulette.

The Underlash Lash Serum: built specifically for DIY extension wearers

Most lash serums are formulated for bare lashes — they don't think about extensions at all. Ours was formulated the other way around.

The Underlash Lash Serum is:

• 100% oil-free — won't interfere with your Bond, Seal, or pre-bonded Quickies strip
• Prostaglandin-free — no iris colour change, no skin darkening
• Peptide-powered — supports the lash growth cycle naturally
• Vegan and cruelty-free
• Hypoallergenic — designed for the same sensitive-eye customers who switched to Underlash because salon glue irritated them
• Safe to use alongside every lash in the Underlash range — The Quickies, The OG Bond & Seal lashes, or no extensions at all

Most users see visible improvement in 4–6 weeks of daily use. The thicker and stronger your natural lashes get, the better your extensions grip and the longer they wear — it's a compounding effect.

How to use lash serum with DIY lash extensions (the right way)

Using the right serum is half the battle. Using it correctly is the other half. Here's the routine that works for DIY extension wearers:

Step 1: Wait 24 hours after a fresh application

If you've just applied a new set of Underlash extensions using The Bond Duo and sealed with The Seal, give the adhesive a full 24 hours to cure before introducing serum. The Quickies have a faster set time but a 24-hour buffer is still your safest bet for maximum wear.

Step 2: Apply at the lash line, not the lash itself

The serum's job is to feed the natural lash follicle, not coat the extension. Use the wand to draw a single, thin line along the upper lash line — like a barely-there liquid eyeliner — and don't sweep upward into the lashes or extensions.

Step 3: Make it the last thing on, the first thing off

Apply serum in the evening, after your skincare is fully absorbed (so it doesn't pick up any face oils), and after Foaming Lash Cleanser if you've cleansed your lashes. Let it dry for 1–2 minutes before bed so it doesn't migrate to your pillow.

Step 4: Be patient — and consistent

Lash serums work on the lash growth cycle, which is roughly 6–10 weeks per follicle. You won't see dramatic results in week one. Daily use for 4–6 weeks is the sweet spot for visible change; 12 weeks for the full effect.

Step 5: Top up your Seal as usual

Whether or not you're using serum, applying a fresh layer of The Seal every 2–3 days is one of the highest-leverage things you can do for wear time. If you're stocking up, the Bond, Seal & Remover Bundle keeps you sorted for about 3–4 months.

Salon extensions vs DIY Underlash vs Quickies: a serum compatibility cheat sheet

Not all lashes have the same rules. Here's how lash serum interacts with each option:

The Underlash Serum is one of the very few lash serums that ticks the boxes for every scenario in this table.

What happens if you use the wrong serum (with photos in your head)

Just so you know what you're avoiding — here's what typically happens when DIY extension wearers use an oil-based or prostaglandin-containing serum:

Days 1–3: Extensions feel slightly looser than usual. You might notice one or two clusters lifting in the shower.

Days 4–7: Outer corners go first — they're the highest-stress placement and the first to feel the oil. You start reaching for The Seal more often.

Week 2: You assume the bond has gone off or that you applied them wrong. You troubleshoot everything except the serum.

Week 4+ (with PGAs): You may notice the skin around your eyes darkening, or your eyes feeling more irritated than usual. Many people only realise the connection when they stop using the serum and the symptoms resolve.

If any of this sounds familiar from a serum you've used in the past, that's why it didn't work for you — not your lashes, not your technique. The serum was working against the system.

Real questions from Underlash customers

These come up so often in our DMs and reviews that they deserve a permanent home.

"I've just put on a fresh set of Quickies — can I use serum tonight?"
Wait 24 hours. The pre-bonded strip on The Quickies sets quickly but giving it a full day of curing before introducing any product to the lash line will give you maximum wear.

"Will the serum wash off my Quickies in the morning?"
No. The serum dries clear at the lash line overnight. By morning it's absorbed. You can shower, cleanse with Foaming Lash Cleanser, and carry on as normal.

"I have sensitive eyes — is the serum safe?"
Yes. Many of our serum customers came to Underlash because salon glue or other lash serums irritated their eyes. The Underlash Serum is prostaglandin-free, fragrance-free and dermatologically formulated for sensitive eyes. As with any new product, patch test on the inside of your wrist for 24 hours before applying to your lash line.

"Can I use it on my brows too?"
Yes. The same peptide complex supports brow follicles. Apply sparingly along sparse areas of the brow.

"How long until I see results?"
Most users see visible thickness and length improvement at 4–6 weeks of daily use. Full effect at around 12 weeks. Stop, and lashes return to baseline within a couple of growth cycles — there's nothing addictive or dependency-forming in the formula.

Your DIY-friendly lash care routine

Here's the order of operations that keeps Underlash extensions on for the full 10 days and keeps your natural lashes growing underneath:

Morning

• Gently cleanse the lashes with Foaming Lash Cleanser — just at the base, with the included brush.
• Pat dry with a clean towel — no rubbing.
• Skip mascara (your extensions are your mascara now).

Every 2–3 days

• Apply a fresh top-up coat of The Seal along the base to lock in the clusters.

Evening

• Cleanse with Foaming Lash Cleanser.
• Finish your skincare (face oils away from the eye area, please).
• Apply Underlash Lash Serum as a thin line along the upper lash line.
• Let it dry 1–2 minutes before bed.

Every 10 days

• Remove with The Remover, let your lashes breathe overnight, re-apply fresh.

Stick with this and you'll get noticeably stronger lashes within a couple of months — which means future sets of Iconic, Natural, or Mood Lashes grip even better.

FAQ

Can you use lash serum with lash extensions?
Yes, you can — provided the serum is completely oil-free and free from prostaglandin analogues. Oil dissolves the cyanoacrylate adhesive used in DIY and salon lash extensions, and prostaglandins carry side effects including iris darkening. The Underlash Lash Serum is formulated specifically for use alongside lash extensions.

Is the Underlash Lash Serum safe for DIY lash extensions?
Yes. Underlash Lash Serum is 100% oil-free and prostaglandin-free. It's formulated specifically to be compatible with DIY lash extension systems including The Quickies and the OG Bond & Seal range.

Will lash serum make my extensions fall off?
Only if the serum contains oil or is applied directly onto the extension. An oil-free serum applied to the lash line (not the lash itself) will not affect wear time.

How long after applying lash extensions should I wait to use serum?
Wait 24 hours after a fresh application — whether you're using The Bond Duo and The Seal, or pre-bonded Quickies. This lets the adhesive fully cure before any product is introduced to the lash line.

What ingredients should I avoid in a lash serum if I wear lash extensions?
Avoid any oils (argan, castor, jojoba, coconut, almond, mineral) and any prostaglandin analogues (bimatoprost, isopropyl cloprostenate, dechloro dihydroxy difluoro ethylcloprostenolamide). These are the two ingredient categories most likely to either shorten extension wear time or cause eye-area side effects.

How long does it take for lash serum to work?
Most users see visible improvement in lash length and thickness at 4–6 weeks of consistent nightly application. Full effect typically takes around 12 weeks, which aligns with the natural lash growth cycle.

Can I use lash serum on my eyebrows too?
Yes. The peptide complex in Underlash Lash Serum supports both lash and brow follicles. Apply sparingly along sparse areas of the brow.

Is lash serum safe for sensitive eyes?
The Underlash Serum is formulated for sensitive eyes — fragrance-free, prostaglandin-free, dermatologically formulated. Many of our customers came to us because other lash serums irritated their eyes. Always patch test on the inside of the wrist for 24 hours before applying to the lash line.

Ready to give your lashes the upgrade?

Whether you're brand new to DIY lashes or topping up an existing routine:

• New to DIY? Start with The Starter Kit — everything you need for your first 4–5 sets, plus instructions.
• Want quick, glue-free? Grab The Quickies — pre-bonded, 5-day wear, no kit required.
• Running low on essentials? The Bond, Seal & Remover Bundle keeps you covered for 3–4 months.
• Ready for the serum? Shop Underlash Lash Serum →

For the full Australian DIY lash experience, browse the full Underlash range or take our lash style quiz to find your perfect set.