Lavender oil is a VERY sensitizing essential oil. All of the "good" comments above are NOT true. Primarily a fragrance ingredient, it may have beneficial properties for skin but is also a potential sensitizer due to its fragrance components. The oil form is more likely to aggravate skin than the extract form, especially if you can detect lavender’s distinctive scent.
In-vitro research indicates that components of lavender oil, specifically linalool and linalyl acetate, can have damaging effects on skin in as low a concentration as 0.25%. When exposed to air, these components oxidize, meaning their potential for causing a reaction increases.
If you’re wondering why lavender oil doesn’t appear to be problematic for some people, it’s because research has demonstrated that you don’t always need to immediately see or feel the sensitizing effects for your skin to suffer damage.