What Is Hippuric Acid?
Hippuric acid, also known as N-benzoylglycine, is a small molecule created when the amino acid glycine joins with benzoic acid. It occurs naturally in many mammals where it helps the body clear certain plant compounds, but the material that shows up in cosmetic labs is almost always produced synthetically for purity and consistency. Modern manufacturing usually reacts glycine with benzoyl chloride in water, then filters and recrystallizes the product to get a fine, white powder that dissolves well in water-based formulas.
Chemists first isolated hippuric acid from horse urine in the 1800s, and by the mid-20th century formulators noticed its ability to soften hair. As cosmetic science advanced it became a niche but reliable ingredient for improving hair feel in both rinse-off and leave-on products. Today you might spot it in conditioners, hydrating hair masks, smoothing shampoos, leave-in sprays and anti-frizz creams, often paired with plant oils or proteins to round out a conditioning blend.
Hippuric Acid’s Cosmetic Benefits/Uses
Its main job in personal care is hair conditioning. Hippuric acid coats the hair shaft with a light, water-friendly film that makes strands feel softer and easier to detangle while helping them retain moisture. This thin layer also smooths the cuticle so hair reflects light better, boosting natural shine without a heavy or greasy afterfeel.
Who Can Use Hippuric Acid
Because hippuric acid is water soluble and lightweight it works for nearly every hair type, from fine and oily to coarse and dry. It does not clog pores so those with sensitive or blemish-prone scalps usually tolerate it well. There are no known concerns for curly or chemically treated hair, and its pH-friendly nature means it plays nicely with color-safe formulas.
The version used in cosmetics is synthesized without animal by-products which makes it suitable for vegans and vegetarians. If the finished product carries a cruelty-free or vegan label it typically refers to both the ingredient and the manufacturing process.
Current research shows no specific risk linked to topical hippuric acid for pregnant or breastfeeding women, yet this is not medical advice. Anyone who is expecting or nursing should check with a healthcare professional before adding new hair or scalp products just to be safe.
Hippuric acid does not increase photosensitivity so it will not make skin or hair more vulnerable to sun damage. It is also odorless, colorless in use and compatible with most common styling and treatment ingredients, making it a low-maintenance choice for daily routines.
Potential Side Effects/Adverse Reactions
Side effects from topical hippuric acid differ from person to person. The points below outline potential reactions, but when the ingredient is formulated and used properly most people will not notice any problems.
- Mild scalp or skin irritation A small number of users may feel temporary tingling or redness, often due to very sensitive skin or an overall formula that is too strong
- Contact allergy Rare cases of allergic dermatitis can occur in those already sensitized to benzoic acid derivatives
- Eye discomfort If product runs into the eyes it can cause stinging or watering until thoroughly rinsed out
- Dryness from overuse Extremely high concentrations could lift too much natural oil leading to a dry feel on hair or scalp
Should any irritation, rash or lasting discomfort occur stop using the product and seek advice from a qualified medical professional.
Comedogenic Rating
Rating: 0 / 5
Hippuric acid is highly water soluble, leaves no oily residue and does not build up inside pores, so it earns a solid zero on the comedogenic scale. This makes it a safe pick for people who are prone to acne or breakouts. Because it lacks heavy lipids it is unlikely to interfere with sebum flow even in leave-on formulations. The only caveat is the overall product: if the formula also contains rich butters or waxes the blend, not hippuric acid itself, could influence pore clogging.
Summary
Hippuric acid is used in cosmetics almost exclusively as a hair conditioning agent. It works by forming a thin, water friendly film over each strand that smooths the cuticle, reduces friction during combing and traps a bit of moisture so hair feels softer and looks shinier. While effective it remains a niche ingredient found mainly in conditioners, masks and a few leave-in sprays rather than in every drugstore shampoo.
Overall safety is high: it is noncomedogenic, vegan friendly and rarely irritates, with side effects limited to uncommon cases of sensitivity. As with any new cosmetic product it is smart to run a quick patch test before full use just to be sure your skin or scalp agrees with the complete formula.