A cosmetic formula is ready for final approval when it has successfully passed stability testing, safety assessment, regulatory review, and performance evaluation, and both the manufacturer and the brand are satisfied with the results. This milestone typically comes after several months of iterative development and testing. Below, we unpack exactly what that process looks like, from the first test to the final sign-off.

What does ‘final approval’ actually mean in cosmetic formulation?

Final approval in cosmetic formulation is the formal confirmation that a formula is stable, safe, compliant, and ready to move into commercial production. It marks the end of the development and testing phase and the beginning of manufacturing at scale. At this point, every stakeholder, the formulator, the safety assessor, and the brand, has signed off on the product.

It is worth noting that final approval is not a single event but the conclusion of a structured process. A formula does not simply get “approved” in isolation. It reaches approval status when all required tests have been completed with satisfactory results, regulatory documentation is in order, and the brand has confirmed the product meets their brief. Only then is the formula considered locked and ready for production.

What tests must a cosmetic formula pass before approval?

Before a cosmetic formula can receive final approval, it must pass stability testing, microbiological testing, safety assessment, and efficacy or performance testing. Each of these evaluates a different dimension of the product, and together they confirm the formula is safe and fit for purpose over its intended shelf life.

  • Stability testing: Confirms the formula maintains its physical and chemical properties under various temperature and humidity conditions over time.
  • Microbiological testing: Verifies the product is free from harmful microorganisms and that its preservative system is effective.
  • Safety assessment: A qualified cosmetic safety assessor reviews all ingredients and their concentrations to confirm the product is safe for consumer use.
  • Challenge testing (preservative efficacy): Specifically tests whether the preservative system can withstand microbial contamination in real-world conditions.
  • Performance testing: Evaluates whether the product delivers on its intended claims, such as moisturisation, cleansing strength, or lather quality.

For natural cosmetics, this testing phase can be particularly nuanced. Natural preservative systems, for example, often require more careful calibration than synthetic alternatives, and stability outcomes can vary more depending on the specific plant-derived ingredients used.

How long does cosmetic formula testing typically take?

Cosmetic formula testing typically takes between three and six months, with stability testing being the main driver of that timeline. Accelerated stability studies can shorten the process, but real-time testing at ambient conditions must run in parallel to generate data that supports a full shelf-life claim.

The exact duration depends on the product type, complexity, and the number of revision cycles needed. A straightforward rinse-off product may move through testing faster than a leave-on serum with active naturals that are sensitive to oxidation or pH shifts. Brands should factor this timeline into their launch planning from the outset, as rushing the testing phase is one of the most common causes of product failures post-launch.

What role does regulatory compliance play in formula sign-off?

Regulatory compliance is a non-negotiable part of the cosmetic formula approval process. In the European Union, all cosmetic products must comply with EU Cosmetics Regulation (EC) No 1223/2009, which requires a Product Information File (PIF), a Cosmetic Product Safety Report (CPSR), and notification via the Cosmetic Products Notification Portal (CPNP) before a product can be placed on the market.

For natural cosmetics development, compliance also extends to ingredient sourcing and labelling. Ingredients must be accurately listed using INCI nomenclature, and any claims made on the packaging must be substantiated. If a formula contains allergens above certain thresholds, these must be declared. Regulatory sign-off is therefore not just a formality but a legal requirement that shapes how the formula is built from the start.

What are the most common reasons a formula gets sent back for revision?

The most common reasons a cosmetic formula is sent back for revision are failed stability results, an ineffective preservative system, a safety concern flagged during the CPSR, or feedback from the brand that the sensory profile or performance does not meet expectations. Each of these can add weeks or months to the development timeline.

  • Stability failure: The formula separates, changes colour, or shifts in pH under testing conditions.
  • Preservative failure: The product does not pass challenge testing, meaning the preservative system needs reformulating.
  • Safety concerns: The safety assessor identifies an ingredient at a concentration that exceeds regulatory limits or poses a sensitisation risk.
  • Sensory or performance feedback: The texture, scent, or efficacy does not match the brand’s brief, requiring adjustments that restart parts of the testing cycle.
  • Labelling or claims issues: The intended product claims cannot be substantiated with the current formulation or test data.

Anticipating these revision triggers early in the formulation process, through thorough ingredient selection and clear briefs, significantly reduces the number of cycles needed before reaching the cosmetic formulation sign-off stage.

Who has the final say on approving a cosmetic formula?

Final approval of a cosmetic formula involves three parties: the qualified cosmetic safety assessor, the regulatory authority (through the notification process), and the brand itself. No single party alone can grant full approval. The safety assessor must sign off the CPSR, the product must be notified to the relevant authority, and the brand must confirm the formula meets their commercial and creative requirements.

In practice, the formulator or contract manufacturer plays a coordinating role, ensuring all documentation is in order and that the formula meets the technical standards required for sign-off. The brand has the final commercial say, but they cannot override a safety or regulatory concern. This shared responsibility is what makes the cosmetic formula approval process robust and trustworthy for consumers.

How Rebel Nature supports your formula approval process

Getting a formula from concept to approved and production-ready is a complex journey, and we guide our clients through every stage of it. As a natural cosmetics contract manufacturer with over a decade of formulation experience, we bring both technical expertise and regulatory knowledge to each project.

Here is what we offer throughout the formula approval process:

  • In-house formulation using a portfolio of over 500 high-quality, ethically sourced natural raw materials
  • Coordination of stability, microbiological, and challenge testing with trusted laboratory partners
  • Support in preparing the Product Information File and aligning with EU regulatory requirements
  • Transparent communication at every stage, including ingredient recommendations and packaging input
  • Flexible production capabilities for both small and large batch sizes once approval is reached

We believe that getting the approval process right the first time saves time, money, and frustration for everyone involved. If you are developing a natural cosmetic product and want a manufacturing partner who understands the full journey from brief to production-ready formula, we would love to hear from you. Get in touch with our team to discuss your project.

Frequently Asked Questions

Can I start manufacturing while stability testing is still ongoing?

It is generally not advisable to begin commercial manufacturing before stability testing is complete, as the formula could still change or fail during that period. However, some brands choose to produce a limited pilot batch once accelerated stability data looks promising, accepting a degree of risk. The safer approach is to wait for at least the accelerated stability results and a satisfactory CPSR before committing to a full production run, particularly if you are investing in custom packaging or large raw material orders.

What is the difference between accelerated and real-time stability testing, and do I need both?

Accelerated stability testing exposes the formula to elevated temperatures and humidity levels (typically 40°C/75% RH) over a shorter period to simulate ageing and predict shelf life quickly. Real-time stability testing runs simultaneously at ambient conditions and generates the long-term data needed to substantiate an official shelf-life claim on your packaging. You need both: accelerated testing to make timely development decisions, and real-time data to satisfy regulatory and safety assessor requirements for a credible, defensible shelf-life period.

How do I know if my natural preservative system will pass challenge testing?

There is no guaranteed way to know before testing, but working with an experienced formulator who has a track record with natural preservation systems significantly improves your odds. Factors such as the product’s water activity, pH, and the specific plant-derived antimicrobials used all influence efficacy. If your formula fails challenge testing, the formulator will typically adjust preservative concentrations, change the system entirely, or modify supporting parameters like pH before retesting — so building revision time into your schedule is essential.

What happens if my formula passes all tests but the safety assessor still raises concerns?

A safety assessor can raise concerns even when individual tests pass if they identify a cumulative sensitisation risk, an ingredient with insufficient safety data, or a concentration that sits at the upper boundary of regulatory guidance. In this case, you will typically need to reformulate by reducing the concentration of the flagged ingredient, substituting it, or providing additional toxicological data to support its use. This is one of the reasons why involving a safety assessor early in the formulation process — rather than only at the end — can save significant time and cost.

Does a formula approval in the EU automatically cover other markets, such as the UK or the US?

No — EU approval does not automatically grant market access elsewhere. The UK has its own regulatory framework post-Brexit, requiring a UK Responsible Person and notification via the UK Cosmetic Products Notification Portal (UK CPNP). In the US, cosmetics are regulated by the FDA under different rules, and the recently enacted Modernization of Cosmetics Regulation Act (MoCRA) has introduced new requirements including facility registration and product listing. If you plan to sell across multiple markets, it is important to discuss this with your formulator and regulatory consultant from the outset, as ingredient restrictions and labelling rules can differ significantly.

What is a 'formula lock,' and why does it matter for production?

A formula lock is the point at which the formulation is officially finalised and no further changes are permitted without triggering a new review cycle. It matters because any modification to ingredients, concentrations, or processing steps after this point — even seemingly minor ones — can invalidate existing stability and safety data, potentially requiring retesting. Brands should treat the formula lock as a firm milestone and avoid requesting last-minute adjustments to fragrance, texture, or active levels once testing is underway, as these changes are far more costly to accommodate than they appear.

How should I plan my product launch timeline to account for the formula approval process?

A realistic launch timeline should work backwards from your target launch date, building in a minimum of four to six months for the full testing and approval cycle — and ideally more for complex natural formulations. Key milestones to plan around include the start of stability testing, receipt of the CPSR from the safety assessor, regulatory notification, and packaging finalisation. Brands that treat the approval process as a fixed-duration phase rather than a flexible one consistently experience smoother launches, fewer delays, and lower reformulation costs.