Phenylbenzimidazole Sulfonic Acid: What Is It, Skin Benefits, Cosmetic Uses & Side Effects

Priya Singh
Fact-Checker: Camila Perez
This article was last updated on: November 25, 2023
Table of Contents

Standing in the beauty aisle, staring at the back of a skincare product, the list of ingredients often feels like a puzzle. Amidst the sea of names that sound more like a chemistry experiment than skin saviors, it’s easy to feel lost. What do these ingredients do, and how do they affect your skin?

One such ingredient that you might spot is Phenylbenzimidazole Sulfonic Acid. The name alone is a mouthful, conjuring images of lab coats and test tubes rather than beauty regimes. It sounds intimidatingly scientific, but what exactly is it?

This article delves into the world of Phenylbenzimidazole Sulfonic Acid, exploring its role in cosmetic products. We’ll unravel the mystery behind this ingredient, discussing why it’s used and what benefits it may offer to your skin.

What is Phenylbenzimidazole Sulfonic Acid?

Phenylbenzimidazole sulfonic acid, often known in the cosmetics world under trade names like PARSOL® HS, Ensulizolel, or iSun HS, is a key ingredient in many skincare products based around sun-protection. It’s a synthetic compound manufactured through a series of chemical reactions involving benzimidazole and sulfonic acid.

The primary purpose of Phenylbenzimidazole Sulfonic Acid in cosmetics is as a UV filter. It works by absorbing ultraviolet (UV) light, specifically UVB rays, thereby protecting the skin from damage caused by sun exposure. This ingredient is typically used in concentrations of up to 8% in cosmetic products.

While it can be found as a standalone product, especially in sun protection formulations, Phenylbenzimidazole Sulfonic Acid is more commonly integrated into a broader mix of ingredients in sunscreens and daily skincare products with SPF protection. This integration ensures a well-rounded defense against UV damage while supporting other skin benefits.

Who Can Use Phenylbenzimidazole Sulfonic Acid?

Phenylbenzimidazole Sulfonic Acid is suitable for a wide range of skin types. Its gentle nature makes it appropriate for individuals with sensitive skin who might find other UV filters irritating. Additionally, its ability to absorb UVB rays without leaving a white cast or heavy residue makes it favorable for those seeking lightweight sun protection.

This ingredient is also suitable for vegans and vegetarians. Being synthetically produced, it does not involve any animal-derived ingredients or by-products, making it an ethical choice for those adhering to plant-based lifestyles.

Pregnant and breastfeeding women can typically use products containing Phenylbenzimidazole Sulfonic Acid. However, it’s always advised to consult with a healthcare provider before incorporating new skincare ingredients into a routine during pregnancy and breastfeeding, to ensure safety and suitability for individual health conditions.

Phenylbenzimidazole Sulfonic Acid Skin Benefits

Phenylbenzimidazole Sulfonic Acid, recognized for its roles as a UV absorber and UV filter, offers a range of benefits for skin health:

  • UV Protection: This ingredient excels in absorbing harmful UVB rays, which are a primary cause of sunburn. By effectively filtering out these rays, it minimizes their penetration into the skin. This action is crucial because UVB rays can lead to various forms of skin damage, including redness and irritation. The absorption process involves the transformation of UV radiation into less harmful forms of energy, like heat, thereby providing a shield against one of the most damaging aspects of sunlight.
  • Prevention of Premature Aging: Exposure to UVB rays accelerates the aging process of the skin, leading to early signs like wrinkles, fine lines, and hyperpigmentation. Phenylbenzimidazole Sulfonic Acid helps in countering this by providing a protective layer against UVB rays. This protection is vital for maintaining the skin’s structural integrity, as UV rays can degrade collagen and elastin — the proteins responsible for keeping the skin firm and elastic. By guarding these proteins against UV-induced breakdown, this ingredient plays a significant role in preserving the skin’s youthful appearance.
  • Uniform Skin Tone: Continuous exposure to UV rays can lead to uneven skin tone and dark spots. By filtering out UVB rays, Phenylbenzimidazole Sulfonic Acid helps in preventing the formation of these spots, contributing to a more even skin tone over time. It works by minimizing the trigger for melanin production — the body’s natural response to UV damage, which often results in pigmentation issues.

It’s important to emphasize that the efficacy of Phenylbenzimidazole Sulfonic Acid in providing these benefits is dependent on its consistent use. The protective layer it forms against UV rays is not permanent and diminishes once the product is no longer on the skin.

Phenylbenzimidazole Sulfonic Acid’s Non-active Cosmetic Uses

In the context of cosmetic ingredients, “non-active” refers to functions that don’t directly contribute to the product’s primary skin benefits but play a vital role in maintaining the product’s overall efficacy and stability.

Phenylbenzimidazole Sulfonic Acid, known for its role in light stabilizing, has several non-active uses:

  • Prolonging Product Shelf Life: As a light stabilizer, it helps in extending the shelf life of cosmetic products. Exposure to light, especially UV light, can degrade certain ingredients, causing them to break down and lose effectiveness over time. By absorbing harmful UV rays, Phenylbenzimidazole Sulfonic Acid prevents this degradation, ensuring the product remains effective and safe to use for a longer period.
  • Maintaining Product Consistency: The stability provided by light stabilizers like Phenylbenzimidazole Sulfonic Acid is crucial for maintaining the consistency and texture of cosmetic products. When ingredients degrade due to light exposure, it can lead to changes in the product’s viscosity or texture. By protecting these ingredients, this compound helps in keeping the product’s original consistency intact, ensuring a uniform application and experience each time it’s used.
  • Preserving Ingredient Efficacy: Besides prolonging shelf life, this light stabilizing function is essential for maintaining the efficacy of other active ingredients in the formula. Active components, especially those sensitive to light, can lose their potency when exposed to UV radiation. Phenylbenzimidazole Sulfonic Acid acts as a shield, absorbing the UV rays and thereby protecting these sensitive ingredients from losing their effectiveness due to light exposure.

Phenylbenzimidazole Sulfonic Acid Potential Side Effects

While Phenylbenzimidazole Sulfonic Acid is generally well-tolerated, side effects and reactions can vary from person to person. This variability is often due to individual differences in skin type, such as sensitivity levels and predisposition to allergic reactions. Factors like genetic makeup, existing skin conditions, and even environmental influences can also play a role in how one’s skin reacts to this ingredient.

Potential side effects may include:

  • Skin Irritation: In rare cases, some individuals might experience redness, itching, or a burning sensation upon application.
  • Allergic Reactions: Although uncommon, allergic responses such as rashes or hives could occur, especially in those with a history of skin allergies.

If you experience any of these side effects while using a product containing Phenylbenzimidazole Sulfonic Acid, it’s advisable to discontinue use immediately and consult a dermatologist or healthcare professional. They can provide guidance on whether the reaction is due to the ingredient itself or a combination of factors, and suggest alternative products or treatments if necessary.

It’s important to note that adverse reactions to Phenylbenzimidazole Sulfonic Acid are rare. Generally speaking, the ingredient is considered safe and effective for most people.

In light of these potential side effects, the importance of patch testing cannot be overstated. Before incorporating a new product into your skincare routine, especially one containing active ingredients like Phenylbenzimidazole Sulfonic Acid, conducting a patch test is crucial. You can refer to our comprehensive patch testing guide for detailed instructions on how to do this effectively. This simple step helps in identifying any adverse reactions before applying the product to larger skin areas, ensuring a safer skincare experience.

Comedogenic Rating

Phenylbenzimidazole Sulfonic Acid has a comedogenic rating of 0/5. This indicates that it is non-comedogenic, meaning it is highly unlikely to clog pores or contribute to acne formation.

This ingredient’s molecular structure and solubility characteristics allow it to be absorbed by the skin without blocking pores or triggering acne. This makes it a suitable option for individuals prone to acne or breakouts.


Success in skincare is often a journey of experimentation, trial, and error. Finding what works for you and maintaining consistency with those products is key. Phenylbenzimidazole Sulfonic Acid stands out for its dual roles in skincare formulations. It serves as a non-active ingredient, enhancing the stability and longevity of products, and as an active ingredient that provides immediate skin benefits, such as UV protection, and aids in preventing premature aging.

This ingredient is recognized for its effectiveness and safety, contributing to its popularity in skincare, particularly in sun protection formulations. It’s commonly found in a variety of products, similar to other UV filters like Avobenzone and Octinoxate, but with the added advantage of being less irritating and more suitable for sensitive skin.

The time it takes to see visible results from using products with Phenylbenzimidazole Sulfonic Acid can vary. While its protective benefits against UV damage are immediate, other benefits, like an improvement in skin tone and texture, may take several weeks of consistent use to become noticeable.

For anyone concerned about incorporating Phenylbenzimidazole Sulfonic Acid into their skincare routine, it’s reassuring to know that it is generally well-tolerated by most skin types, including sensitive and acne-prone skin. Its low risk of side effects and non-comedogenic nature make it a reliable choice for daily sun protection and skincare.

Tell us how you found this article in just a couple of clicks!
Delivered right to your inbox each week. Zero spam, all goodness, opt-out at anytime.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
How did you find this article?
Tell us how you found this article in just a couple of clicks!
Get all our top headlines in beauty.
Delivered right to your inbox each week. Zero spam, all goodness, opt-out at anytime.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Send good feedback:

All feedback is anonymous and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Send bad feedback:

All feedback is anonymous and will be used to improve the quality of our articles.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.