Can I just change the fragrance?

This is the most common request I receive from clients.

At first glance, it seems like a simple request. After all, you're only changing the fragrance—not the formula.

In reality, from a formulation, testing, and regulatory perspective, you may not be developing one product with multiple fragrance options. You may actually be developing multiple individual products, each requiring its own technical assessment.

Why?

Because a fragrance is far more than just a pleasant scent.

Modern cosmetic fragrances are highly complex mixtures containing dozens or even hundreds of ingredients, often including solvents and carrier materials such as dipropylene glycol (DPG), triethyl citrate and other proprietary components. Even when two fragrances smell similar, their chemical composition can be very different. That seemingly small change can influence almost every aspect of your formulation.

Viscosity

One of the most noticeable effects of changing a fragrance is a change in viscosity. This is particularly common in surfactant-based products such as shower gels, shampoos, facial cleansers, and hand washes.

I've seen exactly the same shower gel base filled with different fragrances produce completely different viscosities. One fragrance produced the perfect texture. Another made the product noticeably thinner. A third almost completely destroyed the viscosity. Nothing else in the formula had changed. Only the fragrance.

Colour

Not all fragrances age in the same way.

Some remain virtually colorless throughout the product's shelf life, while others gradually yellow during storage. This becomes especially noticeable in transparent packaging. For example, a blue shower gel may gradually appear green—not because the colorant has changed, but because the fragrance has yellowed over time. For brands investing in premium packaging and product aesthetics, this can become an unexpected quality issue.

Solubility of waxes & butters

Fragrance changes can have an even greater impact in anhydrous formulations such as balms, solid cleansers, body butters, and lip products. Certain fragrance ingredients act as plasticizers or alter the solubility of waxes and butters. This can interfere with the wax crystal network, affecting product firmness, texture, stability, and sensorial profile. In some cases, a different fragrance may even contribute to oil sweating or a softer-than-expected balm.

Preservation system

Fragrances and essential oils often possess antimicrobial properties themselves. However, once incorporated into a cosmetic formulation, they can also influence how the preservation system performs. For example, a fragrance may alter how preservatives partition between the oil and water phases, affecting the availability of the preservative where microorganisms are most likely to grow. This doesn't necessarily mean the preservative system will fail. However, it does mean the risk should be scientifically assessed.

Depending on the nature of the change, repeat preservation (challenge) testing may be recommended.

Packaging Compatibility

Certain fragrance ingredients can interact with packaging materials, leading to compatibility issues such as swelling, softening, cracking, leakage, or migration between the product and the packaging. These interactions can compromise both product quality and packaging integrity.

Depending on the nature of the problem, resolving it may require reformulating the product, selecting a different packaging material or choosing a different packaging format altogether.

Claims & Efficacy

Whether efficacy testing needs to be repeated depends on what your claims are based on. If your product claims rely on the aromatherapeutic properties of essential oils—for example, calming, relaxing, or energizing. Then changing the essential oil blend may require new supporting evidence, such as consumer perception studies. However, if your efficacy claims are based on other active ingredients and those ingredients remain unchanged, replacing the fragrance alone is unlikely to significantly affect efficacy results.

In these situations, a scientific risk assessment may justify using existing efficacy data without repeating the study.

Regulatory Documentation

A fragrance change can also affect your regulatory documentation.

Different fragrances contain different fragrance allergens, which may need to be declared on the label depending on their concentration in the finished product. As a result, changing the fragrance may require updates to the INCI declaration, Cosmetic Product Safety Report (CPSR), Product Information File (PIF), and product label.

Even though the formulation change may appear small, the regulatory implications can be significant.

So, Can You Just Change the Fragrance?

Sometimes. But not always.

Every fragrance change should be evaluated through a scientific risk assessment that considers its potential impact on:

• Viscosity

• Colour stability

• Emulsion stability

• Wax structure and texture

• Preservation system performance

• Packaging compatibility

• Product claims

• Regulatory documentation

In some cases, existing data may remain fully valid. In others, additional testing may be necessary. The decision should always be based on formulation science—not on the assumption that changing the fragrance only changes the scent.

About Me

I'm Justyna Szpak, an independent cosmetic formulation chemist with over 20 years of experience in cosmetic R&D. From my fully equipped laboratory in Ireland, I help brands develop innovative, safe and compliant cosmetic products—from the initial concept through formulation, testing, regulatory compliance, and manufacturing support.

Whether you're creating your first product or expanding an existing range, I'd be delighted to help you bring your idea to life.

contact@skinventions-ireland.ie

Let's create beauty together.