What Is 5-Bromo-5-Nitro-1,3-Dioxane?
5-Bromo-5-nitro-1,3-dioxane is a synthetic ingredient created in the lab by reacting glycerin with bromine and nitric acid to form a small ring-shaped molecule that includes both bromine and nitro groups. These groups give the compound strong antimicrobial power, which is why it first gained attention in the 1970s as a way to keep personal care products free from spoilage. As stricter rules for product safety rolled out over the years, many formulators adopted this molecule because it could guard against a broad range of bacteria, yeast and mold without changing the look or feel of a product.
Today the ingredient is typically dissolved into a liquid concentrate, then added in tiny amounts during the cool-down stage of manufacturing. You will most often spot it on ingredient lists for water-based products such as face masks, serums, moisturizers, hair gels, liquid foundations and cleansing wipes. Its stability over a wide pH range makes it a handy option for both rinse-off and leave-on formulas.
5-Bromo-5-Nitro-1,3-Dioxane’s Cosmetic Benefits/Uses
This ingredient serves one key role in cosmetics.
As a preservative, 5-Bromo-5-nitro-1,3-dioxane helps stop the growth of bacteria, mold and yeast that can spoil a product or trigger skin irritation. By keeping formulas microbe-free throughout their shelf life, it allows brands to offer water-rich products that stay safe and effective even after repeated exposure to air and fingers.
Who Can Use 5-Bromo-5-Nitro-1,3-Dioxane
This preservative is considered suitable for all skin types since it is used at very low levels that remain on the skin only briefly before evaporating or being rinsed away. Oily, dry, combination and normal skin generally tolerate it equally well. Those with very sensitive or compromised skin should pay extra attention to how their skin feels when first using a product that contains it because any preservative has the potential to cause irritation in a small percentage of users.
The ingredient is fully synthetic and does not rely on animal-derived raw materials, so it aligns with vegan and vegetarian lifestyles.
Current data does not show that 5-Bromo-5-Nitro-1,3-Dioxane is absorbed through the skin in meaningful amounts, yet research on pregnant or breastfeeding women is limited. This text is not medical advice, and anyone who is pregnant or nursing should ask a healthcare professional before introducing new skincare products just to be safe.
The molecule is not known to make skin more sensitive to sunlight, so normal sun habits apply. It also does not interfere with common actives such as retinoids, vitamin C or exfoliating acids, making it an unobtrusive background ingredient in most routines.
Potential Side Effects/Adverse Reactions
Side effects from topical use of 5-Bromo-5-Nitro-1,3-Dioxane differ from person to person. The points below outline potential issues although most users will never experience them when the ingredient is used correctly by the manufacturer.
- Skin irritation
- Contact dermatitis in individuals already prone to preservative allergies
- Eye stinging if the product accidentally gets into the eyes before rinsing
- Rare cross-sensitivity with other halogenated preservatives such as bronopol
If any discomfort, redness or itching develops while using a product that contains this preservative stop using it and seek medical advice if symptoms persist.
Comedogenic Rating
Rating: 0
5-Bromo-5-Nitro-1,3-Dioxane is a water-soluble preservative that does not leave an oily or waxy film on skin, so it has no tendency to block pores. Because it is used at very low concentrations and is usually rinsed away or evaporates quickly, the chance of it trapping dead skin cells or sebum is virtually nil.
Suitable for acne-prone and breakout-prone skin.
No studies link this molecule to follicular irritation or increased sebum production, so its presence in a formula should not affect the overall pore-clogging profile of the product.
Summary
5-Bromo-5-Nitro-1,3-Dioxane is a lab-made preservative that keeps cosmetics free of bacteria, yeast and mold by disrupting microbial cell processes. It works at low doses, stays stable across a wide pH range and does not alter texture or scent, making it a convenient choice for water-based formulas.
While not a household name, it is a steady player behind the scenes in face masks, gels and wipes where broad-spectrum preservation is needed without heavy oils or parabens.
Current data shows it is generally safe when used within regulatory limits, with irritation remaining rare. As with any new skincare ingredient it is wise to patch test a product first to check personal tolerance.