Ingredient review
Polyaminopropyl Biguanide
INCI: POLYAMINOPROPYL BIGUANIDE
An effective, low-irritation preservative that helps keep your products safe from germs, but has faced some regulatory scrutiny in Europe.
In plain English
Polyaminopropyl Biguanide (often called PHMB) is a synthetic preservative added to cosmetics to stop bacteria, yeast, and mold from growing. Think of it as a gentle guardian that keeps your products fresh and safe to use over time. It's especially common in products that contain water, like cleansers and wipes, because water can easily grow microbes. Unlike some harsher preservatives, PHMB is generally well-tolerated by skin and doesn't cause stinging or irritation for most people.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is relatively strong for its common cosmetic role.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- strong
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Polyaminopropyl Biguanide is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Polyaminopropyl Biguanide.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
strongThere is a stronger practical or research basis for the ingredient role described here.
What it is
A synthetic, water-soluble polymer that acts as a broad-spectrum antimicrobial preservative. It belongs to the biguanide family, which includes compounds used in medical disinfectants and contact lens solutions.
How it works
PHMB works by disrupting the cell membranes of microorganisms. Its positively charged molecules are attracted to the negatively charged surfaces of bacteria, yeast, and mold. Once attached, it penetrates and damages the cell membrane, causing the microbe to leak its contents and die. This prevents the product from spoiling and keeps it safe for repeated use.
Pros
Gentle on skin
PHMB has a very low irritation and sensitization rate, making it a good choice for people with sensitive skin who react to other preservatives.
Effective at low levels
It works at concentrations as low as 0.1%, meaning you get strong preservation without a heavy ingredient load.
Cons and cautions
EU restrictions for leave-on products
Since 2015, PHMB has been banned in leave-on cosmetics in the European Union due to potential long-term toxicity concerns from animal studies. It is still allowed in rinse-off products.
Not natural or eco-friendly
As a synthetic polymer, PHMB does not fit into natural or organic beauty standards, and its environmental biodegradability is limited.
Best for
- Anyone using water-based cosmetics who wants a well-tolerated preservative
- People with sensitive skin who react to parabens or formaldehyde-releasers
Use caution if
- Those seeking products fully compliant with EU cosmetics regulations for leave-on items (PHMB is banned in leave-on products in the EU)
Usage tips
Safety summary
Polyaminopropyl Biguanide is considered safe for use in cosmetics at concentrations up to 0.5% by the U.S. Cosmetic Ingredient Review panel. It has a low irritation and sensitization profile. However, the European Union has banned it in leave-on products due to concerns from animal inhalation studies showing potential lung effects. For rinse-off products, it remains widely accepted and used globally.
Research notes
Multiple safety assessments by the Cosmetic Ingredient Review (CIR) and the European Scientific Committee on Consumer Safety (SCCS) have evaluated PHMB. The CIR found it safe at up to 0.5% in cosmetics. The SCCS concluded it could not be considered safe for leave-on products due to insufficient data on inhalation toxicity, leading to the EU ban. Studies confirm its broad-spectrum antimicrobial efficacy and low skin irritation potential.
Common label clues
- Typical concentration
- 0.1% to 0.5%
- Regulatory status
- Approved in the US and many other countries for rinse-off and leave-on products up to 0.5%. Banned in leave-on cosmetics in the European Union since 2015 due to potential inhalation and long-term toxicity concerns. Always check local regulations.
- Common uses
- Cleansers, Wipes, Leave-on products, Contact lens solutions
- Environmental note
- PHMB is not readily biodegradable and can accumulate in aquatic environments. Its use in rinse-off products means it can enter wastewater systems, so environmental impact is a consideration.
Good to know
- PHMB is also used in swimming pool disinfectants and contact lens cleaning solutions, which shows its strong antimicrobial power.
- The Cosmetic Ingredient Review (CIR) panel in the U.S. has deemed PHMB safe for use in cosmetics at concentrations up to 0.5%.
Common questions
What is Polyaminopropyl Biguanide in beauty products?
Polyaminopropyl Biguanide (often called PHMB) is a synthetic preservative added to cosmetics to stop bacteria, yeast, and mold from growing. Think of it as a gentle guardian that keeps your products fresh and safe to use over time. It's especially common in products that contain water, like cleansers and wipes, because water can easily grow microbes. Unlike some harsher preservatives, PHMB is generally well-tolerated by skin and doesn't cause stinging or irritation for most people.
What does Polyaminopropyl Biguanide do in a beauty product?
PHMB works by disrupting the cell membranes of microorganisms. Its positively charged molecules are attracted to the negatively charged surfaces of bacteria, yeast, and mold. Once attached, it penetrates and damages the cell membrane, causing the microbe to leak its contents and die. This prevents the product from spoiling and keeps it safe for repeated use.
Is Polyaminopropyl Biguanide safe for most people?
Polyaminopropyl Biguanide is considered safe for use in cosmetics at concentrations up to 0.5% by the U.S. Cosmetic Ingredient Review panel. It has a low irritation and sensitization profile. However, the European Union has banned it in leave-on products due to concerns from animal inhalation studies showing potential lung effects. For rinse-off products, it remains widely accepted and used globally.
Who should be careful with Polyaminopropyl Biguanide?
Those seeking products fully compliant with EU cosmetics regulations for leave-on items (PHMB is banned in leave-on products in the EU)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.