Understanding reactions, spotting the early warning signs, and keeping everyone in your studio safe — from a pro who has experienced both sides of the chair.

In ten years of working full-time as a lash technician — having applied thousands of sets — I’ve had exactly two clients develop a genuine allergic reaction. It’s a very low percentage, but those two cases taught me more about lash safety than any training course ever could. Eventually, I even developed a sensitivity myself. It’s time we had an honest conversation about what’s actually going on.

Why do lash extensions cause allergic reactions?

At present, there is only one way to apply semi-permanent lash extensions: attaching synthetic fibres to the natural lashes, one by one, using a cyanoacrylate-based adhesive. It is a powerful chemical, and currently, there is no way around it.

You may have heard about "sensitive" or "UV" glues marketed as safer alternatives. Whilst they are worth investigating, let’s be clear about how they function:

• Sensitive glues: These contain a lower concentration of cyanoacrylate. This sounds ideal, but a lower concentration of bonding agent usually means weaker eyelash retention. If lashes shed faster, clients return more often, which could mean more total adhesive exposure over time.

• UV glues: These are a genuine innovation and can reduce reaction risk, but despite what some marketing might suggest, they still contain cyanoacrylate. The benefit here is a faster cure time, which shortens the fume release window. They are helpful, but they are not entirely reaction-proof.

• Patch testing is always a good practice, especially for new clients or those who flag previous sensitivities. However, be transparent with your clients: a clear patch test is not a guarantee of safety. Many reactions develop gradually over months or even years of regular appointments.

How common are allergic reactions?

Lash allergies are relatively uncommon and almost always build up gradually rather than appearing out of nowhere. In a decade of full-time work, I only had two clients become allergic — both had been regulars for over two years before showing any signs of sensitivity. Most experienced lash techs report roughly one to two reactions every five years.

The Early Warning Sign: If a client mentions that her eyelids have felt itchy or slightly puffy after appointments, take it seriously. That is not normal; it is the first indicator of a developing reaction. Stop treatments immediately. The best alternative is a lash lift — it uses a completely different chemical process (thioglycolate-based rather than cyanoacrylate) and is usually well-tolerated by those who have reacted to lash adhesive.

Is your technique the culprit?

If you are seeing reactions more often than the average tech, it is usually down to application technique rather than a client’s sudden sensitivity. Common mistakes include:

• Applying too much glue too close to the lid. "Less is more" is the golden rule. The closer the bond point is to the skin, the higher the risk of a reaction.

• Eyes not fully closed. If you tape the lashes upward and expose the waterline, you are dramatically increasing contact with adhesive fumes through one of the most absorbent membranes on the face.

• Glue drops placed too close. Cyanoacrylate fumes aren't just absorbed through the eyes; they are inhaled through the nose and mouth. Keep your glue drop as far from your client’s face as possible.

Can lash technicians develop allergies?

This is the uncomfortable part of the industry that we don't discuss enough. Clients experience occasional exposure, but we are exposed every single working day.

I suffered from migraines for years and assumed it was just due to long hours. It wasn't until I stepped back from lashing to focus on brand building—whilst still working long hours—that the headaches disappeared. Every time I assist at a training session now, they return. The link is unmistakable.

Technician reactions often show up as:

• Persistent headaches or migraines

• Sinus irritation or a runny nose

• Puffy, red, or irritated eyes

• Skin irritation or eczema, particularly on the fingertips from direct adhesive contact

Once a technician develops an allergy, it rarely reverses. Prevention is your only defence.

How to safeguard yourself and your clients

• Ventilate your room properly. If you can, invest in an extractor fan. This is the single most impactful thing you can do for your long-term health as a technician.

• Wear PPE. Make face masks and protective glasses non-negotiable, every single day — not just when you remember.

• Distance the glue drop. Fumes travel further than most people realise, and they are being absorbed the entire time the glue is open.

• Buy from reputable suppliers. Always check that your lash adhesives comply with local safety regulations. All London Lash glues and liquids are fully compliant.

• Diversify your treatment menu. Facials, brow treatments, and lash lifts complement extensions beautifully — they allow clients to spend more per visit and reduce your daily adhesive exposure.

A final word on UV glues

Our UV collection is launching shortly. To be transparent: because UV glues still contain cyanoacrylate, they won't eliminate the risk of reactions entirely. However, the significantly faster cure time means a shorter "fume window" — and over years of daily exposure, that makes a real difference to your long-term health.

If you’d like to be notified as soon as our UV system is live, sign up to our mailing list below.

Wishing you nothing but happy clients and zero reactions.

Hanna Putjato
Passionate lash tech & founder of London Lash

Want to know more about lash safety? [Read more about allergic reactions here].