A synthetic azo dye utilized primarily for its ability to impart a vibrant red-to-pink hue to cosmetic formulations. This water-soluble pigment is valued for its stability and consistency, ensuring finished products maintain their intended aesthetic appeal over time.
- INCI Name:
- Red 33 (or CI 17200 in international markets)
- Chemical/Scientific Name:
- Disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate
- Common Aliases:
- D&C Red No. 33, Acid Red 33, Food Red 12
| Category: | Colors |
| Source Origin: | Synthetic (Coal Tar derivative) |
| Comedogenic Rating: | 1 |
| Primary Industries: | Cosmetics, Personal Care, Pharmaceuticals, Oral Care |
| Solubility: | Water |
At a Glance: Properties & Effects
| Formula Stability: | |
| Texture Enhancement: | |
| Irritation Risk: | |
| Comedogenicity: |
Primary Benefits:
- Provides reliable and consistent product coloring.
- Remains stable across a wide pH range in aqueous solutions.
- Allows for transparent tinting in gel-based or clear liquid formulations.
Potential Risks:
- May cause mild staining on very porous surfaces or hair.
- Potential for sensitivities in individuals with known azo dye allergies.
Biological Action & Cosmetic Profile
Functioning as a secondary colorant, the molecule selectively absorbs light in the visible spectrum to produce a distinct magenta-red hue. It is chemically categorized as an azo dye, characterized by the presence of a nitrogen-to-nitrogen double bond. Unlike active substances that penetrate the epidermal barrier to influence cellular metabolism, this pigment remains on the surface of the skin or within the product matrix. Its primary role is sensory, designed to enhance the user experience by making the formulation visually appealing.Molecular stability is one of the standout features of this colorant. It exhibits high resistance to light degradation and thermal fluctuations, which prevents the product from “fading” on the shelf. In formulations where Aqua is the primary solvent, the dye disperses evenly without the need for high-shear mixing or complex emulsification. This ease of use makes it a staple for formulators creating everything from clarifying shampoos to lightweight facial serums.Structural integrity is maintained even when exposed to oxidizing agents or variations in acidity. While some natural dyes shift color significantly when the pH changes, this synthetic variant remains relatively true to its original shade. Consequently, it is often selected for products where color precision is non-negotiable for brand identity.
Broader Applications & Origins
Synthetic dyes like this one emerged as more stable and cost-effective alternatives to carmine or botanical extracts. Originally derived from coal tar, modern production involves high-purity chemical synthesis to meet strict regulatory limits on heavy metals and impurities. Beyond standard skincare, the dye is frequently utilized in mouthwashes and toothpastes due to its water solubility and safety profile in oral care.Integration into diverse product categories is common. In the hair care sector, it provides the slight pinkish tint found in “color-safe” or “moisturizing” shampoos. In bath products, the high water solubility ensures that the color washes away cleanly without leaving a stubborn residue on the bathtub or the skin.
Routine Integration
Synergies:
- Works harmoniously with Glycerin and other humectants in water-based serums.
- Pairs well with other synthetic dyes to create secondary colors like purples or oranges.
- Compatible with most preservatives including Phenoxyethanol and Sodium Benzoate.
Conflicts:
- No known chemical conflicts with common skincare actives; however, it may visually “bleed” in high-oil anhydrous balms if not properly stabilized.
Clinical Consensus & Safety
Regulatory bodies including the FDA and the European Commission classify this dye as safe for use in cosmetics, subject to specific purity standards. The Cosmetic Ingredient Review (CIR) Expert Panel has evaluated the safety of D&C Red No. 33 multiple times, concluding it is safe for use in topical cosmetics, including those applied to the eye area and mucous membranes. In the United States, it is batch-certified by the FDA to ensure that contaminants such as lead and arsenic remain well below safety thresholds. While azo dyes are occasionally scrutinized for sensitivity, clinical data indicates that this specific dye has a very low potential for dermal irritation or sensitization in the general population.
Is Red 33 safe for sensitive skin?
Yes, it is generally considered safe for sensitive skin. Because it is used in very low concentrations (often less than 0.1%) to color a product, it rarely triggers a reaction. However, those with a confirmed allergy to azo dyes should perform a patch test.
Does this dye stain the skin permanently?
No, it is highly water-soluble. Any temporary tinting of the skin is usually the result of high concentrations in a product and can be easily washed away with water and a mild surfactant.
Why is it called CI 17200 in some ingredient lists?
CI stands for Color Index. International labeling standards often require the Color Index number (17200) instead of the common name (Red 33) to maintain consistency across different languages and regions.