What Is Solvent Red 24?
Solvent Red 24 is a synthetic red dye whose chemical name is 2′,3-Dimethyl-4-(2-Hydroxynaphthylazo) azobenzene. It belongs to the large family of azo colorants, which get their vivid shades from a double nitrogen bond joining two aromatic rings. The pigment is petroleum-derived and does not occur naturally in plants or minerals.
The dye first appeared in the early 1900s to tint plastics, lubricants and printing inks. As cosmetic chemists searched for bright, stable colors that resisted fading, they adopted Solvent Red 24 for makeup in the mid-20th century, following safety reviews by regulatory bodies. Today it is approved for restricted use in certain regions and must meet purity standards before it reaches a cosmetics lab.
Manufacturing starts with aniline and other petrochemical feedstocks. These raw materials go through nitration and reduction steps to form aromatic amines. The key stage is diazotization, where one amine is converted to a diazonium salt then coupled with a second aromatic compound to build the azo bond that creates the dye’s red hue. The crude pigment is filtered, washed and milled into a fine powder before being dispersed in oil or solvent systems suitable for cosmetics.
Because Solvent Red 24 dissolves in oils rather than water, it shows up most often in lipsticks, lip balms, lip glosses, blushers, oil-based makeup removers, nail lacquers, some hair-color rinses and bath oils. It is less common in creams or lotions that rely on water as the main phase.
Solvent Red 24’s Cosmetic Benefits/Uses
This ingredient is used for a single, straightforward purpose in personal care formulations
As a colorant Solvent Red 24 brings a bold, visually appealing red shade to products. It lets formulators create consistent, uniform color that stays true during wear and storage. In lip products it delivers vibrant payoff and can be blended with other pigments to fine-tune tones from soft coral to deep crimson. In nail polish and hair rinses it adds brightness while resisting fading from light and heat, helping products maintain their shelf appeal and performance over time.
Who Can Use Solvent Red 24
Because Solvent Red 24 functions only as a colorant and is used at very low levels, most skin types can tolerate it without trouble. Normal, dry, oily and combination skin usually have no issues. People with highly sensitive or allergy-prone skin could react to any synthetic dye, so they may want to be cautious with products that list this ingredient.
The dye is synthetically produced from petroleum sources, not animals, so it is generally considered suitable for both vegans and vegetarians. Manufacturers normally do not use animal-derived processing aids for this pigment, but those following a strict lifestyle can double-check with the brand for confirmation.
Regulatory agencies have evaluated Solvent Red 24 for topical use during pregnancy and breastfeeding and have set strict purity and concentration limits. When used within these limits it is not expected to pose a risk, yet this is not medical advice. Anyone who is pregnant or nursing should show the full ingredient list of any cosmetic product to their healthcare provider before use, just to be safe.
Solvent Red 24 does not make skin more sensitive to the sun and it is not known to interfere with common skincare actives like retinoids or acids. It is oil-soluble, so it may stain clothes if a richly pigmented product transfers while still wet.
Potential Side Effects/Adverse Reactions
Reactions to the topical use of Solvent Red 24 differ from person to person. The issues listed below are possible but uncommon when the ingredient is used at the levels allowed by law.
- Skin irritation – mild redness, itching or burning can occur, especially on sensitive skin
- Allergic contact dermatitis – rare immune response that may lead to rash or swelling
- Temporary staining – the pigment may leave a short-lived red tint on skin, nails or surrounding surfaces
- Eye irritation – if a loose or creamy formula accidentally gets into the eyes it can cause stinging or watering
- Sensitization over time – repeated exposure in very sensitive individuals could make future reactions more likely
If any of these effects appear, stop using the product and consult a medical professional for advice.
Comedogenic Rating
Rating: 0/5
Solvent Red 24 itself is a finely milled pigment that does not contain fatty acids or heavy oils that could clog pores. It remains dispersed in the base of a formula and is chemically inert, so on its own it does not interact with skin oils or sit inside pores.
Because of this it is generally safe for people who are prone to acne or breakouts. Any risk of clogged pores is far more likely to come from the rest of the product’s ingredients, not the dye.
If a product is very oily or waxy the overall formula could still feel heavy on breakout-prone skin, but that is unrelated to the presence of Solvent Red 24.
Summary
Solvent Red 24 is an oil-soluble synthetic dye used purely to give cosmetics a bright, stable red color. Its azo structure locks in vivid pigment that resists fading from light or heat, letting lipsticks, nail polishes and similar products keep their bold look through wear and storage.
The dye is not a headline ingredient the way hyaluronic acid or vitamin C is, yet it remains a steady performer in color cosmetics where a strong red is needed. Many brands choose it because it delivers reliable shade consistency batch after batch.
Safety reviews by regulators have set strict purity and usage limits that make topical application very low risk. Side effects are uncommon and usually limited to mild irritation in sensitive users. As with any new product it is wise to do a quick patch test before full use, especially if your skin reacts easily.