What Is Myrtrimonium Bromide?
Myrtrimonium Bromide, sometimes listed as tetradonium bromide, is a quaternary ammonium compound made in a lab rather than extracted from plants. Chemists start with a fatty-chain tertiary amine, typically one carrying a myristyl (14-carbon) tail, then react it with hydrobromic acid. The result is a salt that stays solid at room temperature, dissolves easily in water or alcohol and holds a mild, almost neutral scent.
The ingredient first gained attention in the 1960s when formulators looked for alternatives to older, harsher preservatives. Quats like Myrtrimonium Bromide offered broad-spectrum protection against bacteria and yeast without the strong odors of phenolic compounds. Over time its safety record and performance kept it in steady use, and today it shows up in many modern personal care lines.
Because of its stability and low use level it fits well into an array of products. You will most often see it in rinse-off and leave-on hair products such as shampoos, masks, conditioners and serums. It can also appear in facial moisturizers, body lotions, after-shave balms and lightweight styling creams where a gentle preservative is needed to keep the formula fresh during its shelf life.
Myrtrimonium Bromide’s Cosmetic Benefits/Uses
In everyday cosmetics this ingredient serves one key role.
As a preservative Myrtrimonium Bromide helps stop the growth of bacteria, mold and yeast that can spoil a product or irritate skin. By keeping unwanted microbes out it protects both the formula and the user, extending shelf life and supporting overall product safety even at low concentrations.
Who Can Use Myrtrimonium Bromide
Myrtrimonium Bromide is generally well tolerated by most skin and scalp types. Because it works at very low levels and is water soluble it tends not to clog pores or leave heavy residue, making it suitable for oily, dry, combination and even sensitive skin. Those with extremely reactive or compromised skin should still watch for any stinging or redness, as quaternary ammonium compounds can occasionally provoke irritation in very delicate barriers.
The ingredient is produced synthetically with no animal derived components so it is appropriate for vegans and vegetarians. Formulators usually pair it with plant based or synthetic co-preservatives, keeping the finished product free of animal inputs.
Current safety data show no specific hazards for people who are pregnant or breastfeeding when the ingredient is used at the tiny concentrations found in cosmetics. This is not medical advice and anyone who is pregnant or nursing should review any skincare or haircare routine with a qualified healthcare professional before use.
Myrtrimonium Bromide does not increase photosensitivity, so products containing it can be worn during the day without raising sun-related risks. It also plays nicely with color-treated hair and does not react with common actives like vitamin C or retinoids, giving formulators flexibility when building multi-benefit products.
Potential Side Effects/Adverse Reactions
Reactions to topical Myrtrimonium Bromide differ from person to person. The points below outline potential issues users could encounter, though such events are uncommon when the ingredient is included at standard cosmetic levels and the product is properly manufactured.
- Mild skin irritation – transient redness or warmth, more likely on already sensitized skin
- Contact dermatitis – rash or itching in individuals who develop an allergy to quaternary ammonium compounds
- Eye irritation – stinging or watering if a rinse-off or leave-on formula accidentally gets into the eyes
- Scalp dryness or flaking – possible with frequent use of leave-on hair products in users prone to dry scalp
If any of these effects appear discontinue use and seek advice from a medical professional.
Comedogenic Rating
Rating: 0–1. Myrtrimonium Bromide is highly water soluble and used at very low percentages, so it does not build up in pores or form an occlusive film. As a result it is considered non-comedogenic for most users and is generally suitable for acne-prone or breakout-prone skin. No data suggest it promotes blackheads or whiteheads, and its quick rinse-off profile in many hair products further reduces any pore-clogging risk.
Because it is a quaternary ammonium preservative rather than an emollient oil or wax, its molecular structure does not encourage the formation of comedones. Only in rare cases of extreme sensitivity might indirect irritation lead to secondary breakouts.
Summary
Myrtrimonium Bromide acts primarily as a preservative, guarding formulas against bacteria, mold and yeast by disrupting microbial cell membranes. It performs this task efficiently at tiny concentrations, stays stable across a wide pH range and dissolves easily in water which helps keep products clear and light.
While it is not a headline ingredient you will see advertised on bottle fronts, its quiet reliability keeps it in steady rotation behind the scenes in shampoos, conditioners, lotions and creams where brands need a gentle preservative that will not overshadow other actives.
Current research and decades of cosmetic use show a strong safety profile when the ingredient is used as directed. Side effects are uncommon but, as with any new product, patch testing on a small area of skin is a smart precaution to confirm personal compatibility.