What Is Ammonium Nonoxynol-4 Sulfate?
Ammonium Nonoxynol-4 Sulfate is an ammonium salt created by adding a sulfate group to Nonoxynol-4, a compound made from reacting nonylphenol with ethylene oxide. Turning it into a sulfate salt gives it a water-loving head that helps it mix oil and water. The ingredient first appeared in cleansing products in the late 20th century when formulators looked for surfactants that could lift dirt without heavy oils. To make it, manufacturers start with Nonoxynol-4, treat it with sulfur trioxide or chlorosulfonic acid to attach the sulfate group, then neutralize the mixture with ammonia to form the final salt. You will most often see Ammonium Nonoxynol-4 Sulfate in face cleansers, micellar waters, makeup-removing wipes, body washes and some shampoo formulas where gentle yet effective cleansing is needed.
Ammonium Nonoxynol-4 Sulfate’s Cosmetic Benefits/Uses
In personal care products this ingredient plays one main role:
- Cleansing agent: Its surfactant action lowers the surface tension between water and oils, lifting away dirt, sweat and makeup so they can be rinsed off easily. This helps leave skin or hair feeling clean without a heavy residue.
Who Can Use Ammonium Nonoxynol-4 Sulfate
This surfactant is generally suitable for normal, oily and combination skin types because it rinses clean and does not leave a heavy film. Dry or very sensitive skin might find it a bit stripping if used in high concentrations, as the cleansing action can remove some of the skin’s natural oils. People with eczema, rosacea or compromised skin barriers should look for gentler alternatives or formulas where this ingredient is paired with soothing agents.
Ammonium Nonoxynol-4 Sulfate is synthetic and not derived from animal sources so it is typically considered vegan and vegetarian friendly. As always, certification depends on the full formulation and the brand’s sourcing policies.
Current safety data does not flag this ingredient as a problem for women who are pregnant or breastfeeding when used at the low levels found in rinse-off products. This is not medical advice and pregnant or nursing individuals should confirm any skincare routine with their healthcare provider.
The ingredient is not known to increase photosensitivity, so it will not make skin more prone to sunburn. Standard sun protection practices are still recommended for overall skin health.
Potential Side Effects/Adverse Reactions
Responses to topical Ammonium Nonoxynol-4 Sulfate vary from person to person. The effects listed below are only potential issues and are unlikely to occur for most users when the product is properly formulated.
- Mild skin dryness due to its ability to lift away surface oils
- Irritation or stinging particularly on broken or highly sensitive skin
- Contact dermatitis in rare cases for individuals allergic to nonionic surfactants
- Eye irritation if the cleanser is not fully rinsed from the eye area
If any persistent redness, burning or discomfort occurs stop using the product and consult a healthcare professional.
Comedogenic Rating
Rating: 1 (very low likelihood of clogging pores)
Ammonium Nonoxynol-4 Sulfate is a highly water-soluble surfactant that rinses off cleanly instead of lingering on the skin’s surface, so it does not readily mix with sebum or sit inside pores. Because it is used in low concentrations in wash-off products its residue on the skin is minimal, giving it a near non-comedogenic profile.
For most people prone to acne or breakouts this ingredient is considered safe to use.
Formulas that pair it with heavy oils or waxes could still cause congestion, so the overall product composition matters more than this single ingredient.
Summary
Ammonium Nonoxynol-4 Sulfate is primarily a cleansing agent that helps water and oil mix, lifts away grime then rinses off without a film. Its surfactant head loves water while the tail grabs onto oil, allowing makeup, sunscreen and daily dirt to wash down the drain.
It is not a mainstream star like sodium lauryl sulfate or cocamidopropyl betaine, yet it shows up in niche facial cleansers, micellar waters and some gentle shampoos when formulators want mild foaming and easy rinsing.
Current research and industry assessments find it safe for use in rinse-off cosmetics at typical levels with only a small risk of dryness or irritation for very sensitive skin. As with any new skincare product, do a quick patch test before full use to be on the safe side.