How should I dilute grapefruit essential oil for safe skin application?

Grapefruit essential oil is highly concentrated and should never be applied undiluted to the skin. For body massage or cosmetic blends, mix 1–2 drops of the essential oil with 5 ml (about one teaspoon) of a carrier oil such as jojoba, sweet almond, or fractionated coconut oil. This yields roughly a 0.5–1% dilution, which is generally well tolerated for leave-on body products. If you have sensitive skin, start at the lower end and perform a patch test: apply a small amount of the diluted blend to the inner forearm, cover, and wait 24 hours for any reaction. Avoid using on broken or irritated skin. Because citrus peel oils can increase photosensitivity, do not apply diluted grapefruit oil to skin that will be exposed to direct sunlight or UV tanning beds within the next 12–24 hours. If you plan to use it in a facial product, keep the dilution at or below 0.5% (1 drop per 10 ml carrier) and consult a dermatologist if you have a history of reactive skin, rosacea, or are using photosensitizing medications.