Store medicine below 25 degrees C where you can, below 15 degrees C if possible, at under 60% relative humidity, in the dark and without big temperature swings. Cellars, basements and buried caches hold steady cool temperatures; attics, cars and sunlit rooms do not, and bathrooms and kitchens are the worst indoor spots. Insulin needs a refrigerator-range cold chain and must never freeze.
Temperature, humidity and light targets can be approximated without power in a cellar, a basement or a buried cache.
Cool, Dry, Dark And Steady
These targets are rules of thumb from this guide. Where a medicine’s own label gives a storage range, the label’s range comes first.
- Temperature. Below 25 degrees C is good and below 15 degrees C is excellent. Steadiness matters too, so a root cellar, basement or buried cache is better than a room that heats and cools daily.
- Humidity. Below 60% relative humidity. Bathrooms are the worst place, which is ironic given how many people keep medicine there. Kitchens come second-worst.
- Light. Opaque containers. If the container is clear, wrap it in cloth or foil.
- Air. Keep bottles sealed and open them as seldom as possible.
Cold Chain For The Fragile Few
Insulin and other biologics need cooling and must not freeze. Without power, options include a cellar or buried store, a stream-cooled container, or an evaporative clay-pot cooler. Evaporative coolers work by water evaporating from a damp surface, so how well they work depends on local air dryness, and the damp environment is hard on medicine; keep the medicine sealed in waterproof packaging, not exposed to the damp. In a refrigerator, keep insulin away from the freezer compartment and the coldest wall. Insulin that has frozen or been heated should be treated as unreliable; see Medications That Genuinely Expire.
Method: Making A Store
Step 1: Find the coolest, steadiest place you have. Cellars and basements first. Avoid exterior walls that take the sun.
Step 2: Measure if you can. A thermometer shows daily swings. If you have a hygrometer, check humidity.
Step 3: Block light. Opaque boxes or foil-wrapped containers.
Step 4: Keep it dry. Use desiccant and sealed containers as in Repackaging & Desiccants.
Step 5: Separate cold-chain items. Give them their own cooling and check them often.
Common Mistakes
- Choosing a room by convenience. The bathroom is the worst.
- Letting the temperature swing daily. Steady conditions help.
- Putting a damp cooler against open bottles. Moisture is a cause of decay.
Safety
A cache is a hazard if it is forgotten or unlabelled
Medicine buried or hidden in a cellar can be confused with other items, found by children, or leaked into by water. Label every container, record where it is, and keep it away from food, water supplies and anything that could contaminate it.
What’s Next
- Learn next: Repackaging & Desiccants — adding barriers to the store
- Combine with: What Actually Degrades Medications — the causes you are controlling