Humidity and temperature swings make the bathroom a poor storage place for some medicines, cosmetics, textiles and electronics.
Medicines
Many medicines require a dry environment and a specific temperature range. Shower steam creates different conditions, so follow the label and keep medicines away from children.
Spare towels and linens
Clean textiles absorb moisture and odors. If ventilation is limited, store spare towels and linens in a dry cabinet outside the bathroom.
Some cosmetics and perfume
Heat and humidity can change the texture and scent of certain products. Store sensitive cosmetics according to the manufacturer’s recommendations.
Electronics
Even when a device is not near running water, humidity and condensation are not helpful. Chargers and electronics are safer in a dry room.
Bottom line
Keep the solution simple: start with the most likely cause, change one factor at a time, and observe the result. That makes it much easier to identify what actually works in your situation.