Creatine monohydrate is a stable, dry, crystalline powder. Sealed, in a cupboard, it is one of the least fragile things in a supplement cabinet.
What ends it is not age on a shelf. It is water, warmth and time in solution, and those three are worth understanding because they are the ones a household controls.
Does creatine expire?
Dry creatine monohydrate degrades very slowly at room temperature in a sealed container. The reaction that ends it is conversion to creatinine, and it is driven by moisture, heat and acidity rather than by the calendar. A tub kept dry and closed will still be creatine long after the date printed on the lid.
The same powder in a shaker of water is a different situation. Creatine in solution converts steadily, and faster when the water is warm. Mixing a bottle in the morning to drink in the evening is the one common habit that actually costs something, and it is not a habit anyone thinks of as storage.
What does the printed date on a supplement actually mean?
There is no federal requirement in the United States that a dietary supplement carry an expiration or best-by date. If a firm prints one, the manufacturing rules require it to hold data supporting that date. So a missing date is not by itself a defect, and a printed date is worth what the data behind it is worth.
That is the opposite of how the shelf reads. A date looks like a measurement and usually is not published as one. The checkable question is whether the brand will say what the assay read at the end of the stated period — which is a document, not a number on a lid.
Does clumping mean creatine has gone bad?
Clumping means moisture has reached the powder. That is a genuine signal and it is not the same signal as lost potency. Moisture is the condition the conversion needs, so a clumped tub has been given the conditions; it does not follow that much has converted, and there is no way to tell from the outside.
Which produces one rule that is worth more than any date: keep the scoop out of the tub between uses, close it, and store it away from the kettle and the hob. A wet scoop returned to a dry powder is the most common way a household introduces the one variable that matters.
How should creatine be stored?
Dry, sealed, at room temperature, out of direct sun, and away from the humid corners of a kitchen. Mix what is going to be drunk rather than making it up hours ahead. That is the entire protocol, it costs nothing, and it removes the only degradation route that operates on a domestic timescale.
Base Work is a 300 g tub, 60 servings of a 5 g dose, so it is a two-month container by design rather than a year-long one. A tub finished inside two months is a tub that never gets old enough for this article to apply to it.
What the research does not show, including on our own tub
Nobody publishes a domestic stability figure, and that includes us. The conversion chemistry is well described, and the specific question a buyer has — how much creatine is left in this tub after eighteen months in this kitchen — has no published answer, because the conditions are not uniform and no one is funding it.
Our own certificate cannot answer it either, and it is worth being exact about why. Base Work’s document, lot CM20251225A, reports creatine monohydrate at 99.87% against a greater-than-99.5% specification, by HPLC, with a named laboratory and a completion date on it. That is a measured result, and it settles what was in the tub when it was tested. It is not a shelf-life study and it does not pretend to be one: no certificate in this category reports what is left after eighteen months in a warm kitchen, because nobody runs that test. It is transcribed in full on Testing & Certification.
What survives is duller than the question deserves and truer than the answers it usually gets. Keep it dry, keep it closed, drink it soon after mixing, and stop worrying about the date.
More in this cluster: the form comparison, why the gummy format has a stability problem, and how to read a supplement label.