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Cosmetic & over-the-counter (OTC) stability & package compatibility testing

Shelf life & package compatibility

Shelf life testing is an essential part of the development and maintenance of drugs, OTCs, and cosmetics.  ALS has over 30 years of testing the shelf lives for everything from color cosmetics to cytotoxic chemotherapy APIs and Drug products.  ALS data has been used to support numerous product registrations and NDA filings.  Our large volume of chambers and wide range of conditions has us prepared to take on any long or short-term shelf life, or period after opening study.

A stable choice

ALS recognizes the importance of proper shelf life testing before launching new formulas. Improper or incomplete shelf life testing can lead to products going to market that don’t hold up to their claims and can even result in recalls. While there is no one-size-fits-all approach to shelf life testing, we work as your partner to help you decide what is right for you and your budget.

Shelf Life for Cosmetic Products

There are two typical storage conditions for cosmetic products: accelerated and real-time. At each pull point, ALS will test samples of the product for all typical release conditions and ensure the product is still meeting it’s specifications. Samples can be submitted as bulk or in final packaging. Accelerated only may be sufficient to achieve the goals of the product. Our sales team will help you decide what’s right for you.

Shelf life can be combined with package compatibility

In order to achieve endpoints for both formulation stability and compatibility, submit samples in final packaging for stability studies.

 Package Compatibility

ALS regularly performs package compatibility studies. Package compatibility tests whether or not the primary package choice is suitable for the formulation. There is some confusion as to whether or not this is a separate test from stability. If stability is conducted in final packaging then it can cover both shelf life and compatibility goals. However, if bulk was tested for stability, it is necessary to perform a separate study for package compatibility.


ALS will perform all of the necessary tests in-house with fast turnaround at each pull point. These tests can be a part of the stability study and they include: Color/Odor/Appearance, Viscosity, pH, Specific Gravity, Weight loss, Preservative effectiveness, Active Ingredient Assay, or Microbial Limits.

Period After Opening

ALS has a long history working with Period After Opening (PAO) claims. Some markets require a PAO claim on packaging, in addition to a general shelf life claim. The PAO claim is meant to tell the consumer how long the product will last once opened. For these studies, we open products, including “breaking” seals, and close the units again prior to storage. Typical PAO claims are anywhere from six months to two years.


ALS has a state of the art photo stability chamber able to do photo exposures of 1.8 Million lux hours (per ICH guidelines) of visible or UV light. Our chamber is also temperature and humidity controlled.

The window sill

Unlike other companies, ALS does not perform photo light exposure by placing products near a window or on their roof. This method is not controlled and very unreliable, especially because most windows are treated to prevent UV light transmission. We use an actual photo stability chamber, which is a superior method for these studies.

Shelf Life for OTC Drug Products

OTC Drug products, such as sunscreens and acne products, have a higher bar to meet for stability studies than cosmetic products. For these studies, ALS will perform active assay validation prior to engaging in the stability study, and perform both accelerated and real time conditions. We advise you to place three initial lots of a formulation on stability and at least one additional lot every year a specific formulation remains on the market.

Related resources

Batch release services for OTC products

ALS offers fast turnaround times for routine samples, so that your batches are never delayed.