Some medicines include the storage instruction “Protect from moisture.”
This means the medicine should be kept away from humid or damp conditions that could affect its quality, stability, or physical form.
Why Can Moisture Be a Problem?
Moisture can affect certain tablets, capsules, powders, and other dosage forms.
Depending on the product, excess humidity may cause medicines to:
- Soften
- Stick together
- Change texture
- Break down more quickly
- Become less stable over time
MedlinePlus notes that heat, air, light, and moisture can damage medicines.
Is the Bathroom a Good Place to Store Medicine?
Often, no.
Bathrooms can become warm and humid because of showers, baths, and sinks.
FDA and MedlinePlus both advise that damp bathroom cabinets may not be appropriate for many medicines because moisture and temperature changes can affect them.
Where Is a Better Place to Store Medicine?
For many medicines, a cool, dry location may be more appropriate.
Examples may include:
- A bedroom drawer
- A closet shelf
- A storage box
- A kitchen cabinet away from the stove and sink
However, always follow the specific storage instructions for the medicine.
Should You Keep the Bottle Tightly Closed?
If the medicine label or instructions say to keep the container tightly closed, follow that direction.
Some products require the bottle to remain tightly closed between uses to help protect the medicine from moisture.
For example, the current DailyMed labeling for VIOKACE specifically instructs patients to keep the bottle tightly closed after opening and to keep the medicine in a dry place.
What Is a Desiccant Packet?
Some medicine bottles contain a small packet or canister designed to absorb moisture.
This is called a desiccant.
If the product instructions say to leave the desiccant inside the bottle, do not remove it. It is not medicine and should never be swallowed.
Can You Transfer Medicine to Another Container?
Sometimes, but not always.
Certain medicines depend on their original container to help protect them from moisture.
If the label says to keep the medicine in its original container, follow that instruction.
If you are unsure whether a pill organizer or another container is appropriate, ask a pharmacist.
What If the Medicine Gets Wet?
Do not automatically use a medicine that has become wet or exposed to significant moisture.
The safest next step depends on:
- The type of medicine
- How much moisture it was exposed to
- How long the exposure lasted
- Whether the medicine changed in appearance or texture
Ask a pharmacist before using a medicine that may have been damaged by moisture.
Can You Tell If Moisture Has Damaged a Medicine?
Sometimes visible changes occur, but not always.
Warning signs may include:
- Tablets sticking together
- Changes in texture
- Crumbling
- Unusual softness or hardness
- Changes in color or smell
MedlinePlus advises against using medicines that have clearly changed in appearance, texture, or smell.
When to Ask a Pharmacist
Ask a pharmacist if:
- The medicine was stored in a humid area
- The tablets or capsules look different
- The bottle was left open
- The medicine became wet
- You are unsure whether a desiccant should remain in the bottle
- You want to transfer the medicine to another container
Bottom Line
“Protect from moisture” means the medicine should be stored in a dry environment and handled in a way that limits exposure to humidity or water.
Follow the storage instructions on the label, and ask a pharmacist if the medicine may have been exposed to damaging moisture.
Sources
- MedlinePlus — Storing Your Medicines.
- U.S. Food and Drug Administration (FDA) — Don’t Be Tempted to Use Expired Medicines.
- DailyMed — VIOKACE prescribing information.
- DailyMed — Diphenhydramine HCl tablet labeling with “protect from moisture” storage instructions.