Sodium Hydroxide: What Is It, Cosmetic Uses & Side Effects

This article was last updated on: July 25, 2023

The world of cosmetics can be a labyrinth of scientific nomenclature, cryptic labels, and perplexing ingredient lists. From Retinyl Palmitate to Ascorbyl Tetraisopalmitate, the names sound like challenging tongue twisters at best. One component that you might have spotted lurking in the small print of your favorite beauty products is Sodium Hydroxide.

Indeed, “Sodium Hydroxide” might sound a bit intimidating, like something from a high school chemistry experiment. However, it’s far from uncommon in the landscape of cosmetics. Its presence might raise questions in your mind. Why is it used? Is it safe?

This article aims to demystify Sodium Hydroxide and delve deep into its role within cosmetic formulations.

What is Sodium Hydroxide?

Sodium Hydroxide, often known as lye or caustic soda, is an inorganic compound widely used in the cosmetic industry. The powerful alkaline property makes Sodium Hydroxide an excellent pH adjuster or buffer. It helps maintain an optimal pH level in cosmetic products, ensuring they work effectively and remain stable over time.

At the molecular level, Sodium Hydroxide works by neutralizing the acids present in cosmetic formulations. Its use ranges from cleansers and soaps to hair straighteners and depilatories, typically in minimal concentrations.

Who Can Use Sodium Hydroxide?

Considering the skin type, Sodium Hydroxide is generally suitable for all. Given that it’s used in minuscule amounts and as a pH adjuster, it doesn’t interact directly with the skin. As such, people with different skin types, from sensitive to oily, can use products containing Sodium Hydroxide.

From a dietary perspective, Sodium Hydroxide is suitable for both vegans and vegetarians. It’s a mineral-derived ingredient, not of animal origin.

As far as pregnancy and breastfeeding are concerned, Sodium Hydroxide is considered safe to use. It’s used in such micro concentrations that it doesn’t pose any risk. But as always, it’s recommended to consult with a healthcare professional or dermatologist if there are any specific concerns.

Sodium Hydroxide’s Cosmetic Uses

Let’s tap into the cosmetic uses of Sodium Hydroxide. Each one is deeply tied to its official functions—buffering and denaturing.

  • pH Adjustment: The core function of Sodium Hydroxide in cosmetics is to serve as a buffering agent. Maintaining an ideal pH balance in products is crucial to ensure their stability, efficacy, and longevity. Sodium Hydroxide does just that. It neutralizes the acidic components in a formulation, allowing the product to stay within the desired pH spectrum. This is particularly important in skincare products like cleansers and creams, where a too-acidic or too-basic product can disturb the skin’s natural pH balance, leading to various skin issues like dryness, irritation, or breakouts.
  • Enhancing Effectiveness of Other Ingredients: Through pH adjustment, Sodium Hydroxide indirectly enhances the performance of other ingredients in the product. Certain ingredients, like AHAs and BHAs in exfoliators, perform their best at specific pH levels. Sodium Hydroxide helps create that perfect environment, enabling these ingredients to maximize their potential. So when you see remarkable results from your favorite skincare product, you might have this unsung hero to thank.
  • Denaturing Proteins: Sodium Hydroxide is also a denaturing agent. It works by disrupting the natural structure of proteins, which can be beneficial in certain cosmetic applications. For instance, hair relaxers or straighteners often contain Sodium Hydroxide. The ingredient denatures the protein structure of hair strands, making them more manageable and straighter. Similarly, in depilatory creams, Sodium Hydroxide helps in breaking down the protein structure of hair, enabling easy hair removal.

Remember, the role of Sodium Hydroxide in cosmetics is not so straightforward. It often plays a supporting role, enhancing the effectiveness of other ingredients and guaranteeing the ideal pH level for optimal results.

Sodium Hydroxide Potential Side Effects

Like any component of a skincare or cosmetic routine, Sodium Hydroxide’s side effects can vary significantly from person to person. This variation is largely due to the unique nature of our skin. Factors such as skin type, sensitivity, and individual allergies contribute to how our skin reacts to different ingredients. Understanding and identifying your skin type, which you can learn about in detail here, is crucial in evaluating what ingredients might work best for you.

Potential side effects and interactions of Sodium Hydroxide might include:

  • Skin Irritation: For individuals with sensitive skin, products with Sodium Hydroxide might cause mild irritation, such as redness, itching, or a slight burning sensation.
  • Dryness: In some cases, Sodium Hydroxide might contribute to dryness, especially if used in high concentrations within a product.
  • Allergic Reaction: Although rare, an allergic response such as hives or rash might occur in some people.

If any of these side effects happen while using a product containing Sodium Hydroxide, it’s essential to stop using the product immediately and consult a dermatologist or healthcare professional as soon as possible.

However, keep in mind that adverse reactions to Sodium Hydroxide are generally rare. When used in appropriate concentrations, Sodium Hydroxide is considered safe and effective in cosmetics and skincare products.

Finally, while Sodium Hydroxide is generally safe, it’s always wise to conduct a patch test when introducing a new product into your skincare routine. A patch test involves applying a small amount of product to a discreet area of your skin, like the inside of your wrist or behind your ear, and waiting for 24 to 48 hours to see if any reaction occurs. This practice is an essential step in skincare safety and can help prevent potential allergic reactions or irritations. For our comprehensive guide on how to perform a patch test, please follow this link.

Comedogenic Rating

Sodium Hydroxide receives a comedogenic rating of 0. This means that it’s non-comedogenic, i.e., it’s not likely to clog your pores. The rating is attributable to its role in the formulation. It’s not an ingredient that’s designed to sit on the skin or penetrate the pores. Therefore, it becomes an ingredient that those prone to acne or breakouts need not fear.


When it comes to personal care products, not every ingredient is an ‘active’ player impacting the skin directly. Some are like silent supporters, working behind the scenes to create an ideal environment for the real stars to shine. Sodium Hydroxide is one such unsung hero, playing an essential role in maintaining the pH balance and ensuring the overall formulation functions efficiently.

Sodium Hydroxide might not be making the headlines in the beauty world, but it’s a popular ingredient amongst cosmetic formulators. Its scientific moniker may not appear in the marketing materials of your favorite products, but its presence is critical in an array of items, from cleansers to hair straighteners. It’s not a trendy, avant-garde ingredient, but rather a time-tested, reliable workhorse in the cosmetic industry.

Addressing concerns, remember that Sodium Hydroxide is safe to use in cosmetics. It’s important to reiterate that Sodium Hydroxide typically appears in tiny concentrations in cosmetic formulations, which are unlikely to cause harm. However, like any ingredient, individual reactions may vary.

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