How should creatine powder and mixed drinks be stored?

Start with the product

Creatine monohydrate powder, flavoured mixtures, capsules and ready-to-drink products may contain different ingredients and have different packaging. Keep the original label and follow its temperature, moisture and opening instructions. Keep hands and scoops clean and dry; ask the manufacturer if the product has been exposed outside its instructions.1234

What happens in water?

Creatine can convert to creatinine, a different compound, in solution; the rate depends on the conditions. According to the abstract of a 2009 laboratory study, researchers examined creatine crystals and controlled glycerol and buffer mixtures at different water activities and temperatures. The abstract reports high stability of crystals provided they do not absorb enough moisture to dissolve, and degradation in the test solutions. We could not review the full paper. These mixtures were not a shelf-life study of every commercial powder or homemade drink.1234

A study is not a storage instruction

The abstract of a 2003 experiment reports dissolving an effervescent formulation containing di-creatine citrate in deionised water and measuring changes at 4°C and 25°C over 45 days. It reports crystallisation in refrigerated samples and a decline in measured creatine under both conditions. We could not review the full paper, and the abstract does not establish the microbial safety of a prepared drink or a safe number of hours for yours: ingredients, container, hygiene and temperature may all differ.1234

Clumps, expiry and an uncertain history

Clumping can occur for different reasons and does not by itself tell you the product’s potency or whether it is contaminated. A normal appearance cannot prove quality either. If the powder became wet, its seal was damaged or it was exposed to heat, note the product and batch and ask the manufacturer. Do not assume an expiry date can be extended or a damaged product restored by cooling.1234

A mixed drink is also food

Follow the label and the storage requirements of everything added to the drink. Milk and other perishable ingredients introduce food-safety concerns separate from creatine’s chemical stability; clean preparation equipment matters. See storing powders and prepared shakes and the creatine evidence profile.

For a drink containing ingredients that require refrigeration, US FDA food-safety guidance says to refrigerate promptly and not leave perishables at room temperature for more than two hours, or more than one hour when the air temperature is above 90°F (about 32°C). This is food-safety guidance, not a proven shelf life for the creatine itself.1234