Refrigerating the sealed sachet for at least 30 minutes before use adds a measurable cooling benefit. The lower temperature causes temporary vasoconstriction of superficial blood vessels, which can make fluid accumulation under the eyes look less pronounced for a short period. The gel matrix holds cold well, so the patches stay cool throughout the 15–20 minute wear time. This is a physical effect, not a pharmacological one — it does not "drain" lymph or permanently change tissue, but many people find the sensation refreshing and the visual improvement helpful before makeup or an event.
Storage notes: Keep the unopened sachets in a cool, dry place away from direct sunlight. Short-term refrigeration (a few hours to overnight) is fine; do not freeze — the gel structure can rupture, making patches fragile and uneven. If you store them in the fridge long-term, let the sachet sit at room temperature for 2–3 minutes before opening so condensation doesn't dilute the serum. Once opened, use both patches immediately; the remaining serum oxidizes and loses efficacy quickly. Discard any patch that has dried out or changed texture.