Heat and light speed up oxidation in essential oils, changing their scent and increasing the risk of skin sensitization over time, with citrus oils like lemon and sweet orange affected most due to their high limonene content [1][2]. Jojoba oil, the carrier used in How Majesstic Botanicals' roll-ons, is a liquid wax ester rather than a true oil, making it naturally resistant to oxidation and shelf stable at room temperature [3][4]. To protect a roll-on through summer, keep it out of direct sunlight, store it in a cool dry place, keep the cap tightly closed between uses, and use it within one to two years of purchase.

Essential oils are chemically active liquids, and heat speeds up the natural process of oxidation that changes their scent and reduces their shelf life. Citrus oils are especially heat and light sensitive, while a carrier like jojoba oil is naturally far more stable. Understanding this is the difference between a roll-on that still smells vibrant in September and one that's gone flat, or worse, more likely to irritate skin.