Can I add grapefruit essential oil to my existing skincare products, and what should I watch for?

Grapefruit essential oil can be incorporated into fragrance-free carrier creams, lotions, or facial oils at a low dilution — typically 1 drop per 10 ml of product (0.5%) for face, or up to 2 drops per 10 ml (1%) for body. Mix thoroughly in a clean small container rather than directly in the original jar to avoid contaminating your main product. Because the oil is cold-pressed from peel, it contains naturally occurring limonene and other volatile compounds that may oxidize over time; use your custom blend within 4–6 weeks and store it in a dark glass bottle away from heat. Do not combine in the same application with strong actives such as high-percentage vitamin C (L-ascorbic acid), AHAs/BHAs, or retinoids, as the combined potential for irritation and photosensitivity increases. If you use prescription topical treatments, check with your dermatologist before adding citrus essential oils. Always apply sunscreen (SPF 30+) during the day when using grapefruit oil in leave-on products, even at low dilution, due to the photosensitizing potential of citrus peel constituents.