IFRA Category Selection: Which Applies to Your Product — 4, 5A or 5B?

How "safe" a fragrance oil is cannot be determined in a vacuum. The same scent does not carry the same risk in a perfume applied to the skin as it does in a room spray. When the top note fades, exposure takes centre stage — and that is precisely where IFRA steps in.

IFRA builds its rules not around the scent itself, but around how the product is used. The logic is straightforward: the more intense and prolonged the skin contact, the lower the permitted usage level.

The International Fragrance Association (IFRA) divides products into specific categories within the framework of the currently applicable amendment. IFRA sets these rules by product type, and under IFRA 51 it defines 12 categories; each category has a maximum percentage that must not be exceeded.

The primary aim of these restrictions is not toxicity panic but, in most cases, the management of skin sensitisation risk (an allergic response that develops through repeated contact). The IFRA classification system categorises fragrances according to their potential skin sensitisation risk; these categories help manufacturers, formulators and regulators determine appropriate usage levels across different product types.

These three categories are often confused because all of them involve products that contact the skin. But the distinction is clear: where is the product applied, and with what intensity? Everything else follows from the answer to that question.

Category 4 covers fine perfumery in the classic sense. Category 4 encompasses fragranced products typically applied to the neck, face and wrists — for example, hydroalcoholic and non-hydroalcoholic fine fragrances and fragranced wristbands. Under Amendment 51, "all types of aftershave" have been explicitly clarified as falling within Category 4.

Category 5 is the family of leave-on products applied to the face and body by hand, and it is subdivided into four groups. 5A covers lotion-type, predominantly leave-on products applied to the body by hand — all body creams, oils and lotions (excluding baby products), foot-care products, insect repellents applied to the skin, and all powders and talcs (excluding baby powder). 5B covers predominantly leave-on moisturising products applied to the face by hand: face creams, toners and facial moisturisers.

Choosing a category is not guesswork. Ask a few questions about your product in order, and you will land in exactly one box. Everything else is your call.

1. Is the product applied to the skin?

   If not (room fragrance, diffuser, candle) — look at categories outside 4/5. If yes, continue.

2. Is it a fragrance or a care product?

   If it is a scent-focused product that is sprayed or dabbed on (perfume, cologne, aftershave), the direction is Category 4.

3. If it is a leave-on care product: where is it applied?

   Over a large body surface (lotion, body cream) → 5A. On the face (face cream, toner) → 5B.

4. Separate out special cases.

   Hand cream falls under 5C, and baby products under 5D — these are distinct sub-categories. 5C covers hand creams, nail care and hand sanitisers; 5D covers baby creams, lotions, oils and powders. Do not conflate them with 5A/5B.

5. Consult the IFRA documentation for the fragrance oil.

   Once you have identified the correct category, read the maximum usage level permitted for that category from the fragrance-specific IFRA certificate. The limit varies from fragrance to fragrance.

That final step is critical: two different fragrance oils in the same category may have entirely different permitted levels. (See How to Read an IFRA Certificate and How to Calculate the Maximum Usage Level.)

You have chosen your category and set your level. Now, when turning the formula into reality, two pitfalls await: weight-versus-volume confusion and the "higher concentration = longer-lasting scent" fallacy.

Longevity is not the same as concentration. The primary determinant of sillage and longevity is not the fragrance oil percentage but the volatility of the raw materials. A citrus-heavy 25% extrait may fade quickly, while an amber, oud or musk-heavy formula at 10% can linger for hours. The EDP/EDT/parfum distinction is often presented as purely a matter of concentration, but concentration alone does not determine performance — formula composition and volatility do. Do not promise precise hour ranges; every formula writes its own story.

Grams or ml? Building formulas on a gram (g) basis is best practice, but do not overlook density differences. The specific gravity of fragrance oils and solvents varies considerably: citrus oils run at approximately 0.84 g/ml, while heavy resins and some synthetic materials can exceed 1.10 g/ml. If you quote only grams and ignore the ml conversion, you will encounter overflow or shortfall when filling bottles by volume.

Category knowledge alone is not enough. Safety is determined not by the source but by the molecule and the usage level. This final layer is the framework that makes your formula both safe and compliant.

The perception that "natural is safe, synthetic is risky" is incorrect. Some of the allergens subject to the strictest IFRA restrictions — such as Citral, Eugenol and Oakmoss — are found in the highest concentrations in natural essential oils. Natural bergamot is phototoxic and can cause permanent pigmentation marks on skin exposed to sunlight. By contrast, certain pure synthetic materials such as Ambroxan and Iso E Super are almost entirely safe from an allergenic standpoint. Safety depends on the molecule and the usage level, not on the source.

Amendment 51 is a concrete product of this scientific approach. It contains more than 40 new standards alongside seven revised ones, grounded in considerations such as skin sensitisation, systemic toxicity, depigmentation and potential genotoxicity. In other words, the limits are not arbitrary — they are based on RIFM research.

The regulatory side: In Turkey, "product notification" (the process) and the "responsible person/manufacturer obligation" (liability) are two separate matters. Do not conflate the notification steps with legal responsibility. For definitive procedures, required documentation and penal provisions, consult the current TİTCK source.

Note: IFRA standards are updated regularly and the applicable amendment is subject to change. This article explains general principles; for definitive category definitions, current limits and legal obligations, always refer to the fragrance oil's current IFRA certificate and official sources. For Turkey's cosmetic regulations, product notification requirements and penal provisions, verify against current legislation via TİTCK / official sources.