A sample that looks right on the day it is approved can separate, change colour, lose its scent or thicken in the container months later, on a shelf in a warmer climate than the lab. Stability, compatibility and preservative-efficacy testing exist to find that before production rather than after a complaint. They also produce the data your importer will ask for when filing in the destination market, so it pays to know what to ask for while the tests are being planned, not after they have finished.
💬 Sunsho Trade manages own-brand cosmetics made in Japan for brands outside Japan, with a GMP-certified partner factory in Japan. Tell us where your product will be sold and we will make sure the test plan covers it.
There is no single Japanese protocol, so the factory designs the programme
Japan has no single statutory protocol for cosmetic stability testing; the factory designs a programme for each formula, and your job is to make sure it reflects your container, your market and your importer’s needs.
This surprises brands that expect a fixed national test. In practice the factory decides which conditions to test, how long to observe and what counts as a pass, based on the formula type and its own experience. That flexibility is useful, because a toner and a sunscreen behave very differently, but it means the programme is only as relevant as the information the factory receives.
The conditions a stability programme typically covers fall into a few categories. We describe them as categories on purpose: the actual temperatures and durations are set by the factory for each formula, and we do not quote them.
| Test category | What it looks for | Why it matters for an export product | What to ask for |
|---|---|---|---|
| Storage at raised, low and room temperature | Changes in appearance, colour, odour, viscosity, pH or separation over time | Your product may spend a long time in transit and storage in conditions unlike the lab | The conditions used, the observation points and the result at each |
| Temperature cycling | Whether repeated warming and cooling breaks an emulsion or causes crystals | Shipping routes and warehouses expose products to swings | Whether cycling was run, and the outcome |
| Light exposure | Colour change or fading of the formula or the print | Clear or translucent containers on a lit shelf | Whether it was tested in the actual container |
| Container compatibility | Interaction between formula and container, seals and pump parts | The product lives in the container for its whole shelf life | Confirmation that the final container and closure were used |
| Preservative efficacy (challenge test) | Whether the preservative system reduces microorganisms deliberately added | Daily use introduces microorganisms, especially from jars | The method followed and the result summary |
Container compatibility: test in the real pack
Compatibility testing only means something if it is run in the final container and closure, so the container has to be chosen before the test starts.
A formula sits against the container wall, the seal and the pump parts for its whole life. Oils and fragrance can interact with some plastics. A pump can corrode or clog. A tube can lose its seal or take up part of the formula. None of this shows in a glass lab jar.
That is why the container belongs in the brief. If you approve the formula in a stock container and choose the real container later, the compatibility work happens twice. If you change the container after testing, ask the factory which tests have to be repeated; the answer depends on how different the new container is. The choice of container, and who supplies it, is covered in containers and packaging for Japan-made cosmetics.
If you supply your own containers, deliver them early. The factory cannot start compatibility testing until it has the real thing.
Preservative efficacy: the challenge test
A challenge test adds known microorganisms to the product and checks whether its preservative system brings them down over a set period; it tells you whether the product protects itself in use.
Every opening and every touch introduces microorganisms. The preservative system has to cope with this for the product’s life after opening. In Japan, preservatives must come from Appendix 3 of the Standards for Cosmetics, a positive list with limits that differ by product type, which is why a preservative system that works in another market may have to change. The full check is explained in checking a formula against Japan’s Standards for Cosmetics.
Two practical points follow for the brand. First, the container affects the result: a jar opened and touched daily asks more of a preservative system than an airless pump. Tell the factory which container and use pattern to assume. Second, a formula marketed with fewer or no listed preservatives still needs protection from microbial growth by some means, such as the container, the formula’s own make-up, or other ingredients. Discuss with the factory how that protection is achieved and how it is tested, before you plan any label wording about preservatives, and check that wording with your importer against the destination’s rules.
Japan’s Standards for Cosmetics are Ministry of Health and Welfare Notification No. 331 of 29 September 2000, applied from 1 April 2001. Checked against the published texts of the Ministry of Health, Labour and Welfare and the Japan Cosmetic Industry Association on 17 October 2026.
💬 Not sure whether your jar or preservative choice will pass? Send us the draft ingredient list and container and we will raise it with the factory before testing starts.
The Japanese expiry-date rule, and why export markets differ
Japanese rules require an expiry date only for cosmetics whose properties and quality may change within a defined period after manufacture under appropriate storage; the threshold usually cited is three years from manufacture, but confirm this against the current ministerial notice before you rely on it.
In other words, a cosmetic shown to stay stable beyond that threshold under appropriate storage is not required by the Japanese rule to carry an expiry date, while one that may change within it is. Stability data is what tells you which side of that line your product falls on. Article 61 of the PMD Act (Japan’s Act on Securing Quality, Efficacy and Safety of Products Including Pharmaceuticals and Medical Devices) lists the expiry date among the label items “where required”.
This matters for products sold in Japan. For export products, your destination market applies its own date rules. Many markets use a period-after-opening symbol, require a date of manufacture or a best-before date, or set their own conditions. Check with your importer which date or symbol your market requires, and make sure the stability and challenge-test data supports it. A period after opening, for example, is a claim about the product’s behaviour in use, and the challenge test is part of the evidence behind it.
What data to ask for in an export dossier
Ask for a written summary of each test, stating the formula version, the container, the conditions, the observation points and the conclusion, and agree in advance what your importer may see.
Your importer files the destination notification, and some authorities ask for evidence of stability or microbial quality, or ask the importer to hold it on file. Ask your importer which documents the authority wants. For Vietnam, see Vietnam’s cosmetics import notification.
A useful test summary from the factory states:
- the formula version or code tested, matching the approved sample;
- the container and closure used;
- the conditions and observation points of each test category;
- the observed results, including any changes noted;
- the conclusion, for example the shelf life the factory considers supported;
- for the challenge test, the method followed and the result.
Factories often prefer to share a summary rather than raw laboratory records, because raw records can reveal formula details. Agree early what you will receive and confirm with your importer that a summary is enough. If the authority wants something more detailed, raise it before the test starts so the factory can plan the report. The other Japan-side documents, from the certificate of analysis to export certificates, are explained in export documents and certificates.
When a change means re-testing
Any change to the formula, the container or a raw-material source can affect stability, so ask the factory whether a change needs new testing before you approve it.
Changes that commonly raise the question:
- a new fragrance, or a different level of the same fragrance;
- a different colour or colourant;
- a featured ingredient added, removed or changed in level;
- a different container material, closure or pump;
- a new supplier for a key raw material;
- a move from one product size to another in a different container.
The factory decides the scope of re-testing for each change. Some changes need only a short confirmation; others need a new programme. Build this into decisions about line extensions: a range of several scents on one base raises the question once for each scent, not once for the range. The trade-off between adapting a base formula and developing a new one is covered in stock base formula or custom formula.
How we manage testing
We tell the factory where and how the product will be sold, make sure the test plan uses the final container, and collect the summaries your importer needs.
Sunsho Trade is a Japanese-managed trading company in Ho Chi Minh City. With a GMP-certified partner factory in Japan, we manage testing as part of the project: passing on your market, container and use pattern, agreeing what the test reports will contain, and checking that the date or symbol on your label matches what the data supports. The full sequence from brief to shipment is in the Japan cosmetics OEM guide.
💬 Planning a launch and need the test data to line up with your importer’s filing? See how our Japan cosmetics OEM service works, read the Japan cosmetics OEM guide, or send us your timeline and market.
Frequently asked questions
1. Is there an official Japanese stability test my product must pass?
No single statutory protocol exists for cosmetic stability testing in Japan. The factory designs a programme for each formula, typically covering storage at different temperatures, temperature cycling, light exposure and compatibility with the container.
2. Does a Japan-made cosmetic always carry an expiry date?
Not under the Japanese rule. An expiry date is required for cosmetics whose properties and quality may change within a defined period after manufacture; the threshold usually cited is three years from manufacture, which you should confirm against the current notice. Your export market may require a date or a period-after-opening symbol regardless.
3. What is a challenge test?
A preservative-efficacy test. Known microorganisms are added to the product and the test checks whether the preservative system reduces them over a set period. It shows whether the product can protect itself during normal use after opening.
4. Why do I need to choose the container before testing?
Because compatibility testing is only valid in the final container and closure. If the container changes after testing, part of the work may need to be repeated. Bring the container decision into the brief.
5. Will the factory give me its full test records?
Factories often share a written summary rather than raw records, because raw records can reveal formula details. Ask your importer what the destination authority needs, and agree the content of the summary with the factory before testing starts.