As we move from the spring season into the heat of summer, your empty capsules, if not stored and handled properly, may begin to suffer from the effects of high temperatures. When capsules are made and shipped, they contain a critical amount of moisture.
Stable gelatin capsules will contain moisture from 13 to 16%, and HPMC capsules from 3 to 8%. The capsules will only maintain proper shape and function if storage conditions are properly kept. For gelatin capsules, this range is 59-77 degrees F; for HPMC, the range is 59 – 86 degrees F.
This is important when capsules are stored in the warehouse, or when in the filling room, and even before and after packaging. Consider capsules a little bit like chocolate in this way; if they get too hot, it will affect the quality, and your experience using them.