Perfumes and room fragrances may contain undisclosed allergens at levels high enough to trigger serious reactions in people with sensitivities, according to new research from Kennesaw State University. A chemistry student investigating fragrance products discovered that some items, particularly plug-in room fragrances, contain allergen concentrations so elevated they exceeded the study's measurement scale even after dilution.

What Allergens Are Hiding in Your Fragrances?

Kennesaw State University senior Ariana Mitchell spent the past year analyzing two common fragrance allergens found in everyday scented products: D-limonene and linalool. D-limonene is a natural compound derived from citrus fruit peels, while linalool comes from flowers and herbs, particularly lavender. Using a laboratory technique called gas chromatography-mass spectrometry (GC-MS), which heats allergens into gaseous molecules and separates them for precise measurement, Mitchell identified and quantified these substances in perfumes, body mists, and plug-in room fragrances.

The research revealed a critical gap in consumer protection: not all allergens contained in a fragrance product appear on ingredient labels, and when they are listed, manufacturers typically do not disclose the actual concentration levels used. This lack of transparency stems from loose regulatory oversight in the fragrance industry, leaving consumers with sensitive skin or fragrance allergies largely unprotected.

Why Are Plug-In Fragrances More Concentrated Than Perfumes?

Mitchell's findings showed a striking difference between product categories. Plug-in room fragrances contained significantly higher concentrations of allergens compared to traditional perfumes and body mists. The reason is straightforward: plug-in fragrances are engineered to scent an entire room, requiring much higher allergen loads to achieve that effect. In some cases, the allergen concentrations were so extreme that they exceeded the study's measurement capacity even after the samples were diluted for testing.

"The plug-ins are more concentrated because they have to fragrance an entire room, so they tend to have a lot more allergens, so much so that it actually goes completely off our scale even after diluting it," said Ariana Mitchell.

Ariana Mitchell, Senior, Kennesaw State University

For consumers with fragrance sensitivities, this concentration difference has real health implications. Mitchell warned that exposure to high allergen levels could trigger serious reactions, particularly in vulnerable populations.

How to Reduce Your Exposure to Hidden Fragrance Allergens

• Check Product Labels Carefully: Look for D-limonene and linalool listed in the ingredient section, though be aware that not all allergens may be disclosed due to current regulatory gaps. If you have known sensitivities to citrus or floral scents, these are red flags to avoid.
• Avoid Plug-In Room Fragrances if Sensitive: Based on this research, plug-in fragrances contain significantly higher allergen concentrations than perfumes or body mists, making them riskier for people with fragrance allergies or asthma.
• Test Products in Small Amounts First: Before using a new fragrance product regularly, apply a small amount and monitor for reactions such as headaches, respiratory irritation, or skin sensitivity over several hours.
• Request Concentration Information from Manufacturers: Contact fragrance companies directly to ask about allergen concentrations in their products. Consumer demand for transparency can push companies toward better labeling practices.
• Consider Fragrance-Free Alternatives: For people with significant sensitivities, unscented or fragrance-free products eliminate the allergen exposure entirely while still delivering the product's primary benefits.

The research underscores a broader concern in the fragrance industry: the lack of mandatory allergen concentration disclosure. While some allergens are required to be listed on labels, manufacturers are not obligated to specify how much of each allergen is present in the final product. This creates a situation where consumers cannot make fully informed decisions about their exposure risk.

"This research is important because it can help warn consumers, especially those with sensitivities, about which products or scent types they may need to avoid. By understanding what's inside these fragrances, we can empower consumers to make safer, more informed choices," said Wei Zhou.

Wei Zhou, Associate Professor of Chemistry, Kennesaw State University

Mitchell's findings have serious implications for people with fragrance allergies or asthma. In extreme cases, exposure to high concentrations of these allergens could trigger asthma attacks severe enough to require urgent medical care, particularly if someone is unaware they are allergic to the substance. This risk is especially concerning for individuals who use multiple scented products throughout the day, compounding their total allergen exposure.

The study forms the foundation of Mitchell's honors capstone project and has already been presented at multiple academic conferences, including the 2025 and 2026 Symposiums of Student Scholars and the 2026 Georgia Collegiate Honors Conference. Mitchell hopes her research will encourage regulatory agencies to scrutinize fragrance products more closely and push manufacturers toward greater transparency in product labeling. Her work demonstrates how student-led research can uncover gaps in consumer protection and drive meaningful change in industry practices.