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Every day, millions of individuals wear perfumes, wash their clothes with scented detergents, or switch on an air freshener without a second thought. What few realize is that this invisible cloud of fragrances is increasingly becoming a cause of medical concern. In dermatology and allergy clinics, fragrances are among the leading contact allergen groups, and their role as inhaled irritants is also raising concerns among clinicians managing individuals with asthma and other respiratory conditions. Exposure is constant, cases are increasing, and many patients are still undiagnosed.

Fragrances are not a single substance but complex mixtures of tens or even hundreds of chemical compounds. Their use extends well beyond perfumery; they are present in cosmetics, hygiene and cleaning products, textiles, and indoor spaces. EU regulation itself acknowledges that these substances are used “widely (…) in perfumes, cosmetics, and also in detergents and household products,” which is why the regulation of fragrance allergen labelling within the EU has begun to tighten.

In this context, fragrances are increasingly recognized as a significant component of everyday chemical exposomes.

Allergic Reaction

Perfume allergy is a form of allergic contact dermatitis (ACD), a delayed-type immune reaction. It occurs when certain molecules act as haptens that penetrate the skin, bind to proteins, and trigger an immune response that can persist throughout life. This results in cutaneous inflammation that may manifest as eczema, pruritus, erythema, or scaling.

However, reactions are not limited to the skin. In some cases, respiratory symptoms such as cough or dyspnea may occur, as well as neurologic symptoms including migraines or headaches — factors that complicate the diagnosis. One clinically important characteristic is that sensitization can develop after years of apparently tolerated exposure, making it difficult to find the trigger allergen.

Recent epidemiologic data confirm that fragrance allergies are common but likely underdiagnosed. Internationally, the prevalence of contact allergy to fragrances in the wider population is estimated to be between 0.7% and 2.6%, whereas in patients undergoing patch testing for dermatitis, recent clinical series report rates of 10%-15%, with a higher prevalence among women with hand and facial involvement.

Prevalence Data

In Spain, fragrances are the second most common cause of ACD after metals. The prevalence in the wider population is estimated to be approximately 1.7%-4.1% across different studies. Epidemiologic surveillance data, however, showed that fragrances play a leading role in cutaneous allergies.

The 2024 data from the Spanish Registry for Research in Contact Dermatitis and Skin Allergy (REIDAC) confirmed that cosmetic-related allergens, including fragrances, remain the primary drivers of sensitization in patients evaluated by patch testing.

Recent data from the Spanish baseline patch test series showed that Fragrance mixtures I and Fragrance mixtures II, along with compounds such as oxidized limonene and linalool, act as relevant haptens, even in pediatric and adolescent populations, with sensitization prevalence rates ranging from 1% to 4%.

The European Surveillance System on Contact Allergies, a working group of the European Society of Contact Dermatitis identified fragrances, including natural perfumes such as mosses and balsams, among the most frequent causes of ACD.

This gap between the wider population and clinical diagnoses suggests an underdiagnosis or misattribution of symptoms.

Causative Allergens

From a chemical standpoint, the problem lies not in the perfume itself but in its components. Fragrances containing multiple molecules with allergenic potential. Among the most relevant are limonene, linalool, and geraniol, which are all widely used in cosmetics. These ingredients can be oxidized upon exposure to air, thereby increasing their capacity to induce allergies.

Scientific evidence confirms that although hundreds of perfuming compounds are present in everyday products, from cosmetics to detergents and air fresheners, only a relatively small group accounts for most contact allergy cases.

A 2024 review published in Acta Dermato-Venereologica found these allergens as primary contributors to clinical burden.

Of particular diagnostic relevance are the standard patch test mixtures Fragrance Mix I and Fragrance Mix II. These compositions include widely used natural substances in perfumery, such as extracts from Peru balsam (Myroxylon pereirae) and moss extracts, in particular oakmoss (Evernia prunastri) and treemoss (Evernia furfuracea). An extract from Treemoss has shown sensitization prevalence rates of 2%-3% in patients with dermatitis.

The chemical behavior of fragrances upon air exposure is also relevant. Common compounds, such as limonene and linalool, present in many fragranced products, can spontaneously oxidize and generate derivatives with significantly greater sensitizing potential. This explains why allergic reactions occur even in previously tolerant individuals and why these compounds are increasingly detected in patch testing, particularly in younger populations.

Diagnostic Testing

The diagnosis of fragrance allergy falls primarily to the dermatologist and is based on patch testing, the clinical standard for identifying cutaneous sensitization. This procedure involves applying a panel of allergens to the skin for 48 hours and evaluating the inflammatory response. The test does not encompass all implicated compounds; therefore, its accuracy depends on adequate substance selection and requires correlation with the patient’s actual exposure history.

In Spain, the REIDAC and updated baseline series recommend including Fragrance Mix I and Fragrance Mix II, Peru balsam, oxidized limonene, and linalool among routine test allergens given their established relevance in ACD. Nevertheless, recent evidence continues to emphasize the need for regular updating of these diagnostic panels because of the constant emergence of new compounds in the cosmetic industry.

These diagnostic limitations mean that a patient may be allergic to a substance not included in the standard test panels and may remain undiagnosed for years.

Respiratory Impact

Beyond the skin, fragrances present in air fresheners, scented cleaning products, colognes, and aerosol sprays are sources of exposure to volatile organic compounds. These substances can react with air to generate secondary particles that can affect the respiratory system, particularly in individuals with chemical hypersensitivity.

A study on individuals with asthma found that more than 40% reported adverse effects associated with fragranced products, including breathing difficulties, asthma exacerbations, headaches, and mucosal symptoms, with consequences for professional and social functioning. Specifically, 41% reported problems when using air fresheners or deodorizers, 42.3% after remaining in spaces cleaned with fragranced products, and 46.2% when people nearby used fragrances.

A 2024 review in the Journal of Asthma and Allergy examined strategies to reduce inhaled contaminant exposure in asthma and found that compounds present in perfumes and deodorants act as low-intensity irritants that are capable of inducing inflammation and functional alterations in the airway, although evidence of respiratory immunologic sensitization remains limited.

Indoor Contamination

Air fresheners, aromatic candles, scented detergents, and fabric sprays release complex mixtures of chemical compounds into indoor environments. Although these products are widely associated with well-being, their cumulative impact on health is being reassessed. These emissions can generate ultrafine particles, secondary chemical byproducts, and chronic low-level chemical exposure.

In this context, the concept of “indoor pollution” has emerged to describe the accumulation of fragrances in indoor spaces such as offices, shops, hospitals, and public transport — a phenomenon that can degrade indoor air quality and limit access to these environments for people with asthma or chemical hypersensitivity.

Specialists consider fragrance-related indoor air contamination potentially comparable in impact to other recognized pollution sources, particularly in enclosed spaces. These findings support the recommendation to limit intense ambient fragrances in shared environments, such as schools, hospitals, public transport, and workplaces, especially where people with asthma, chronic obstructive pulmonary disease, or chemical sensitivities are present.

Regulatory Response

In response to these concerns, the EU has moved to strengthen labelling requirements for fragranced products. Regulation (EU) 2023/1545 amends cosmetic legislation to improve the identification of allergens in cosmetics, easing their avoidance by sensitized individuals.

The regulation expands the declared allergen list from 24 to 80 fragrance allergens that must be disclosed when they exceed specified thresholds: 0.001% for leave-on products and 0.01% for rinse-off products. This expansion incorporated 56 new substances with established allergenic potential.

This change requires greater transparency in cosmetics, hair care products, creams, detergents, and fabric softeners, which must declare compounds by their International Nomenclature of Cosmetic Ingredients when they exceed thresholds. Structural limitations persist; however, the term “parfum” continues to allow complex mixtures to remain undisclosed, the list covers only a fraction of the thousands of compounds in use, and interpretation of the labelling depends entirely on the consumer.

Furthermore, many products labelled as “fragrance free” nonetheless contain aromatic substances serving other technical functions — fragranced preservatives, for example — and clinical guidance therefore stresses the importance of reading specific ingredient lists rather than relying on commercial claims alone.

Overall, what begins as an everyday routine — applying perfume to the skin, scenting clothing, or freshening up a room — can become a health problem. Undoubtedly, fragrances rank among the leading contact allergens and inhaled irritants for sensitive individuals. Exposure is constant, composition is highly variable, and diagnosis is not always straightforward. Perfume remains a cultural and sensory pleasure, but evidence compels us to recognize it as a ubiquitous chemical exposure that, for a segment of the population, has clinical consequences.

This article was translated from El Médico Interactivo, part of the Medscape Professional Network.