Germall Plus is a broad-spectrum preservative used in cosmetics and personal care products to prevent the growth of bacteria, yeast, and mold. It’s a patented blend of two antimicrobial ingredients dissolved in a solvent, and it works at very low concentrations, typically 0.1% to 0.5% of a finished product. You’ll find it in lotions, creams, serums, conditioners, and other water-containing formulations.
What’s in the Blend
Liquid Germall Plus contains three components. The first is diazolidinyl urea, a formaldehyde-releasing preservative that targets bacteria. The second is iodopropynyl butylcarbamate (often abbreviated IPBC), which is particularly effective against fungi, yeasts, and molds. These two active ingredients are dissolved in propylene glycol, a common cosmetic solvent that helps them mix evenly into water-based formulations.
The combination is what makes the product useful. Diazolidinyl urea handles bacterial contamination while IPBC covers fungal threats. Together, they protect against a wider range of microorganisms than either ingredient could alone, which is why the blend is described as synergistic.
How It’s Used in Formulations
Germall Plus is water-soluble, which makes it straightforward to incorporate into the water phase of emulsions or any water-based product. It’s commonly found in lotions, creams, conditioners, hair masks, serums, water-based face masks, and formulas containing botanical extracts or proteins (ingredients that are especially vulnerable to microbial growth).
One critical detail for anyone formulating with it: Germall Plus is heat-sensitive. It needs to be added during the cool-down phase of production, after the product has dropped below high temperatures. Adding it while the batch is still hot is a common mistake that can significantly reduce its preservative effectiveness. It works across a broad pH range of 3 to 8, which covers the vast majority of cosmetic products. It’s also compatible with most standard cosmetic ingredients, so it rarely causes formulation conflicts.
It is not suitable for aerosol products and should be evaluated carefully for leave-on products intended for children.
Safety Profile
The Cosmetic Ingredient Review (CIR) panel, an independent body that evaluates cosmetic ingredient safety in the U.S., has assessed diazolidinyl urea and concluded it can be safely used in cosmetic products at the minimum effective concentration, not exceeding 0.5%. In repeat insult patch testing on volunteers without pre-existing skin conditions, diazolidinyl urea was not a sensitizer and was not a photosensitizer at 0.25%.
That said, the ingredient does have a notable caveat. Diazolidinyl urea is a formaldehyde releaser, meaning it slowly releases small amounts of formaldehyde as part of its antimicrobial action. The CIR review found no indication that diazolidinyl urea in cosmetic products releases formaldehyde at concentrations exceeding recommended safety limits. For most consumers, this poses no problem. However, in clinical patch testing of patients with existing skin conditions, 57 out of 2,385 individuals showed allergic reactions to 1.0% diazolidinyl urea. People with known formaldehyde sensitivity or contact allergies are the most likely to react.
IPBC, the antifungal component, has its own regulatory history. It’s generally considered safe at the low concentrations present in the Germall Plus blend, but some regulatory bodies restrict its use in certain product types, particularly those for lip application or products designed for children under three.
Why Formulators Choose It
Germall Plus occupies a practical middle ground in cosmetic preservation. It’s effective at low usage rates, works across a wide pH range, dissolves easily in water, plays well with most other ingredients, and covers both bacterial and fungal contamination in a single addition. For DIY formulators and small-batch producers, this simplicity is a major selling point. Rather than trying to combine multiple preservatives and test their compatibility, a single addition of 0.1% to 0.5% Germall Plus handles the job.
The main reasons some formulators avoid it are the formaldehyde-release concern and growing consumer preference for “formaldehyde-free” labels. Products marketed as natural or clean beauty often opt for alternative preservative systems, though those alternatives frequently require higher usage rates, narrower pH windows, or more complex formulation strategies to achieve equivalent protection. For products where reliable, cost-effective preservation is the priority, Germall Plus remains one of the most widely used options in the industry.