How should I store this lavender essential oil and how can I tell if it has gone bad?

Essential oils are sensitive to light, heat, and air, so proper storage makes a real difference. Keep the 10 ml bottle tightly closed when you are not using it, and store it upright in a cool, dark place such as a cupboard or a drawer. Avoid bathrooms where humidity and temperature fluctuate, and keep it away from windowsills, radiators, and kitchen stoves. A dark glass bottle already protects the oil from light, but an additional outer box or a dark cabinet adds extra protection.

Lavender essential oil does not spoil in the same way food does, but it can oxidize over time. Oxidation happens when the oil is exposed to oxygen, and it can make the scent less fresh or slightly sharper. If the oil develops an off smell, a noticeably thicker texture, or any visible cloudiness, it is better to stop using it. With proper storage, a bottle of lavender oil can remain aromatic for several years, but the 10 ml size is small enough that most people finish it long before that.

To get the most out of the oil, always replace the cap immediately after use and do not leave the dropper or bottle open while you prepare a blend. If you use the oil in an aroma lamp, do not pour unused oil back into the bottle, as water or residue can contaminate the remaining oil. Keep the bottle out of reach of children and pets, and remember that this product is for external and aromatic use only, not for ingestion.