What Is Phosphoric Acid?
Phosphoric acid, also called orthophosphoric acid, is a clear, colorless liquid made from the naturally occurring mineral phosphorus. In a lab or factory it is produced by treating phosphate rock with sulfuric acid or through a cleaner process that burns elemental phosphorus then hydrates the resulting oxide. The finished ingredient is a water-soluble acid that is easy to handle and blend into liquid or cream formulations.
Chemists first explored phosphoric acid in the early 1800s while studying fertilizers. Its ability to control acidity soon caught the attention of food and beverage makers, and cosmetic chemists later borrowed the idea to help stabilize skin care formulas. Today it turns up in many everyday products such as face masks, exfoliating gels, daily moisturizers, hair conditioners and brightening serums, where only a small amount is needed to fine-tune the product’s pH.
Phosphoric Acid’s Cosmetic Benefits/Uses
In personal care products phosphoric acid plays one main role.
As a buffering agent it keeps a formula’s pH in the desired range so the product stays gentle on skin or hair and the other active ingredients remain effective. A stable pH also helps prevent changes in color, scent or texture during the product’s shelf life.
Who Can Use Phosphoric Acid
Because only small, well controlled amounts are used in cosmetics, phosphoric acid is generally considered safe for all skin types including oily, dry, sensitive and mature skin. People with very reactive or broken skin should be cautious since any acid can add a slight sting if the skin barrier is already compromised.
The ingredient is synthetic or mineral derived, with no animal inputs, so it is suitable for vegans and vegetarians.
Pregnant or breastfeeding women can usually use products that contain phosphoric acid at cosmetic levels, but this is not medical advice. Anyone who is expecting or nursing should show the full ingredient list of any new product to their doctor before use, just to be safe.
Phosphoric acid does not increase photosensitivity, so it will not make skin more prone to sunburn. Normal daytime sun protection habits are still advised for overall skin health.
Potential Side Effects/Adverse Reactions
Side effects from topical phosphoric acid vary from person to person. The following issues are possible yet uncommon when the ingredient is used at the low levels found in finished cosmetics.
- Temporary stinging or burning right after application
- Redness or mild irritation, especially on very sensitive skin
- Dry or tight feeling if the formula is left on for a long time or layered with other strong actives
- Allergic contact dermatitis in rare cases
- Eye irritation if product accidentally gets into the eyes
If you experience any of the above reactions stop using the product and consult a healthcare professional if symptoms persist or worsen.
Comedogenic Rating
Rating: 0 out of 5
Phosphoric acid is a water-thin, completely water-soluble acid with no oily or waxy components that could block pores. It is used at very low percentages simply to fine-tune pH, not to coat the skin or leave a residue. Because of these properties it earns a solid 0 on the comedogenic scale.
This makes it suitable for people who are prone to acne and breakouts.
Unlike some richer acids or fatty alcohols, phosphoric acid rinses or absorbs away without forming a film, so it has virtually no chance of trapping dead cells or sebum. Its only job is pH control, which ends once the product dries or is rinsed off.
Summary
Phosphoric acid’s main job in cosmetics is buffering. By donating or accepting hydrogen ions it keeps a formula’s pH in the sweet spot where the product stays stable, active ingredients work as intended and skin feels comfortable.
It is a background player rather than a headline ingredient, so you will not see it advertised on the front of the bottle, yet it quietly supports everything from moisturizers to hair masks. Formulators value it for being dependable, inexpensive and easy to blend.
When used at the tiny amounts typical in personal care, phosphoric acid is considered very safe. Reports of irritation are low, and it is non-comedogenic, vegan friendly and pregnancy compatible for most users. As with any new product though, a quick patch test is wise to make sure your skin agrees with the full formula.