Oil will worsen the condition of the face. There can be several causes why your skin would turn dark or you may get pigmentation. Sun tan, overweight, pigmentation disorders like acanthosis nigricans or melasma, nutritional deficiency etc are some conditions. Unless someone examines you, we cannot know the cause. Unless we find out the cause it is difficult and pointless to treat. Please send photos with detailed history using online consult option for examination and proper treatment.,

Not much use..Undergo glutathione therapy.... Otherwise, few creams also available.. contact me by direct online consultation for treatment.

Essential oil will not reduce pigmentation, in fact it may make things worse by sensitizing your skin to sunlight thereby causing more pigmentation. For any type of skin, especially for the face, dermatologically formulated bland moisturisers are better. Further, use of essential oils on the face can cause or aggravate pimples and hence should be used with care. You need to use sunscreens to prevent further pigmentation and use specific depigmenting agents for the dark areas. For more details, feel free to consult me online.