As a professional nail technician, understanding the ingredients in your products is just as important as mastering your application technique. UV gel polishes are formulated using a mix of active monomers, photoinitiators, pigments and functional fillers. While these ingredients enable the products to deliver long-lasting wear and beautiful finishes, they must be handled with respect, especially when it comes to potential allergens.
In this guide, we break down common UV gel nail polish ingredients by their function and their allergen risk, from high to low. But remember: even low-risk ingredients should be handled with care and in accordance with best professional practices.
High-Risk Allergens (Use with strict caution)
1. HEMA (2-Hydroxyethyl Methacrylate)
A powerful adhesion promoter, commonly used in base coats and primers. Highly effective but widely recognised as a high-risk allergen when improperly applied or overexposed. Due to its small molecule size, it has higher potential to penetrate the skin. HEMA is permitted in concentrations up to a maximum of 35% under EU regulations and any products containing HEMA must state “for professional use only” and “may cause an allergic reaction” on the label.
Use only in properly formulated concentrations and avoid skin contact at all costs.
2. Di-HEMA Trimethylhexyl Dicarbamate
A common alternative to HEMA in base and builder gels, offering strong adhesion with reduced risk, but still classified as a known allergen.
Often seen in “HEMA-free” products, but not completely allergen-free.
3. Isobornyl Acrylate
Used to enhance flexibility and flow of gel products. Strong adhesion properties, but may cause sensitivity reactions in some individuals.
Found in many hybrid gels.
4. Isobornyl Methacrylate
Very similar to the above, but derived from methacrylate chemistry. Can trigger allergic responses in sensitive individuals.
Common in long-wear top coats and hard gels.
5. Hexanediol Diacrylate
A reactive diluent used to adjust viscosity. Known to cause allergic reactions in susceptible clients or nail professionals.
Ensure proper curing and always avoid overexposure.
6. N,N-dimethylacrylamide
A chemical component used to improve film-forming properties and cure strength. Rarely used in high concentrations but still classed as a high allergen potential.
7. Trimethylolpropane Trimethacrylate (TMPTMA)
A crosslinking monomer used to enhance hardness and adhesion in gel formulations.
TMPTMA is a known skin sensitiser and is frequently cited in allergy reports related to nail products. It can penetrate damaged skin or cuticles, increasing allergy risk.
Use with extreme caution, especially in products applied close to the cuticle area. Avoid skin contact entirely.
Medium-Risk Ingredients (Moderate care required)
8. Hydroxypropyl Methacrylate (HPMA)
Used similarly to HEMA but with a larger molecular size, making it less likely to penetrate the skin and trigger reactions.
Still requires careful handling and professional application.
9. Bis(methacryloyloxyethyl) Hydrogen Phosphate
A bonding agent commonly used in adhesion-promoting products. Allergen potential is lower than HEMA, but can still be sensitising.
10. Acrylates Copolymer
A combination of acrylate monomers that give structure and flexibility to gel polishes.
Generally low-risk unless contaminated or used incorrectly.
11. PEG-4 Dimethacrylate
A combination of acrylate monomers that give structure and flexibility to gel polishes.
Generally low-risk unless contaminated or used incorrectly.
Bis-HEA Poly(1,4-butanediol)-9/IPDI Copolymer
A urethane acrylate oligomer offering flexibility and excellent adhesion.
Urethane-based acrylates like this carry a sensitisation risk, though typically less so than simple monomers like HEMA.
13. Bis-hema Polyneopentyl Glycol Adipate/IPDI Copolymer
Another flexible urethane acrylate used for durability and chemical resistance.
While derived from HEMA, the modified copolymer structure may reduce penetration potential, thus slightly reducing allergen risk.
Low-Risk/Functional Ingredients
10. Phosphoric Acid
Often used in very small amounts to improve adhesion or balance pH. Not commonly associated with allergic reactions.
11. Bis(4-methylphenyl)phosphinyl oxide
A photoinitiator that helps the gel cure under UV/LED light. Used in extremely small amounts.
While it plays a crucial role, it's not considered a common allergen.
12. Ethyl Trimethylbenzoyl Phenylphosphinate
Another photoinitiator, particularly effective in LED formulas. Very low allergen potential.
13. Hydroxycyclohexyl Phenyl Ketone
Yet another photoinitiator, frequently found in LED gels. Typically safe when used in trace amounts.
14. Mica, Polyethylene Terephthalate (PET), Bentonite, Silica
These are used for colour, shimmer, and consistency. Considered inert and low risk when encapsulated in cured gels.
Risk increases if inhaled as dust—wear PPE when working with loose pigments.
15. Dimethicone
A silicone used to add smoothness and shine. Low allergen risk and generally well-tolerated.
16. Polyurethane-33
A high-performance film former that adds strength and flexibility to UV gels.
Polyurethane-33 is considered a low-sensitising ingredient due to its high molecular weight and structure, making it less likely to cause reactions in comparison to smaller, reactive monomers.
Best Practice Tips for Safety & Prevention
Even low-risk ingredients can cause problems when used improperly. Follow these essential safety tips to reduce the risk of sensitisation for both you and your clients:
-
Avoid all skin contact – always apply products with precision and wipe away any excess immediately.
-
Do not apply to compromised nails – avoid application to infected, damaged, or broken skin.
-
Limit over-buffing – over-preparing the nail plate increases permeability and the risk of reaction.
-
Always wear nitrile gloves (6mil minimum) – and change them after every client using the no-touch method.
-
Cure properly using the correct lamp – follow the manufacturer’s instructions to ensure a full and even cure.
-
Apply products thinly – especially base and top coats to allow full penetration of UV/LED light.
-
Hand washing is essential – ask clients to wash hands with warm soapy water after top coat is cured and before applying any oils or balm.
-
Consultation is key – ask clients if they’ve ever experienced a reaction, note changes in medical history, and document all products used at each appointment.
Understanding Labels
Cosmetic labels must list ingredients in descending order of concentration, by weight, as per regulatory standards in many regions (such as the FDA in the U.S. and the EU Cosmetics Regulation in Europe).
Here are the key points:
Ingredient Listing Rules
- Descending Order: Ingredients present at concentrations greater than 1% must be listed in descending order by weight.
- Below 1%: Ingredients used at 1% or less can be listed in any order, after the ingredients above 1%.
- Colour Additives: These can also be listed in any order, usually at the end.
- INCI Names: Most countries require the use of standardised INCI (International Nomenclature of Cosmetic Ingredients) names, not common names.
Final Thoughts
Working safely with gel products is all about education and precision. Many of the ingredients we use every day have the potential to cause reactions—but with correct formulation, thorough application, and good hygiene practices, that risk is significantly minimised.
Look for brands that comply with EU Cosmetic Regulations 1223/2009, and always request or download the Safety Data Sheets (SDS) for the products you use. These will detail each ingredient’s concentration and safety profile. Be confident in asking questions about their manufacturing processes - are their manufacturers inspected and certified by global assurance companies such as SGS and Intertek? Have they been independently assessed in accordance with ISO 22716 Good Manufacturing Practices (GMP)?
Your professional knowledge, hygiene standards and product choices are what keep your clients safe—and your career sustainable.