Is Thioglycolate Safe in Lash Lifts? What the Research Really Says

When it comes to lash lifts, one question that often comes up is: Is thioglycolate safe? After all, it’s a chemical that actively changes the structure of hair. The short answer is: yes — when used correctly and professionally, thioglycolate is considered one of the safest and most reliable reducing agents in cosmetic hair treatments.

Below, we’ll break down what thioglycolate does, what the research says about its effects, and why it continues to be trusted in salons worldwide.

How Thioglycolate Works on Hair

Hair is primarily made up of keratin proteins, about 90% by weight (Ghanem et al., 2025, p. 4). These proteins are rich in the amino acid cysteine, which forms disulfide bonds — the “glue” that gives hair its strength, flexibility, and shape (Ghanem et al., 2025, p. 4).

When performing a lash lift, we’re temporarily breaking some of these disulfide bonds through a controlled reduction process, which “relaxes” the keratin structure so it can be reshaped around a curl rod or pad (Ghanem et al., 2025, pp. 4–5). Once the desired shape is achieved, an oxidizing agent like hydrogen peroxide or bromate reforms the bonds in the new configuration, making the curl or lift permanent (Ghanem et al., 2025, p. 5).

This chemical reaction — breaking and reforming bonds — is the foundation of all perming and lifting services.

What the Research Says About Safety

Thioglycolates (TGA) have been widely used in hairdressing for decades. As Manuszak (1993) noted in her comparative study, “TGA has maintained its position in waving due to its excellent safety record after many years on the market” (p. 21).

Why? Because thioglycolate’s action on hair is both predictable and controllable: under salon conditions, only 13–43% of disulfide bonds are typically reduced for a good result — well below the levels that would cause severe structural damage (Manuszak, 1993, p. 21).

In fact, thioglycolate is even described as “essentially nonallergenic in man due to its excellent safety record” (Manuszak, 1993, p. 21). This is an important distinction, especially when comparing it to newer reducing agents like cysteamine, which can behave more unpredictably and are more sensitive to formulation pH.

Are There Any Risks?

Like any chemical service, overprocessing can cause damage. Research shows that excessive reduction can increase porosity, weaken mechanical strength, and even fade pigment (Ghanem et al., 2025, p. 5). Hair treated with thioglycolate also becomes more hydrophilic, which can lead to dryness and frizz if not properly conditioned (Zhang et al., 2015, p. 5).

However — when applied properly by a trained professional and neutralized correctly, most of these risks are minimal and the hair retains most of its original properties (Manuszak, 1993, p. 76).

Even untreated hair shows damage over time due to weathering and UV exposure, which means proper aftercare is always important, whether you’ve had a lift or not (Manuszak, 1993, p. 83).

Why Professionals Still Choose Thioglycolate

In short: thioglycolate remains the gold standard because it’s safe, effective, and reliable — provided the service is done professionally.

As one study concluded:

“Thioglycolic acid, which is the most common reducing agent, is considered essentially nonallergenic in man due to its excellent safety record after many years on the market” (Manuszak, 1993, p. 79).

Newer alternatives like cysteamine are promising but have not yet demonstrated the same long-term track record of safety and consistency.

Key Takeaways

• Thioglycolate works by breaking and reforming disulfide bonds in keratin — the key to shaping hair safely and effectively.

• Decades of research confirm its predictable performance and excellent safety record when used properly.

• Overprocessing or improper technique can still cause damage — professional application and good aftercare are essential.

• For clients with sensitive skin or lashes, a consultation with a trained lash artist is always recommended.

If you’re curious about whether thioglycolate-based lifting is right for you, don’t hesitate to ask your technician about the products and techniques they use.

References

Ghanem, H., et al. (2025). Effects of thioglycolate compounds in an emerging technique in the world of cosmetics—brow lamination.

Manuszak, M. A. (1993). A study of the effects of reduction by cysteamine and ammonium thioglycolate on the physical and chemical properties of hair (Master’s thesis, University of Cincinnati). University Microfilms International.

Zhang, Y., et al. (2015). Effect of shampoo, conditioner and permanent waving on the molecular structure of human hair.