You may use straight lemon juice or you may dilute it with equal amounts of water and lemon juice for a less harsh application.Other methods of diluting the citric acid in lemon juice include adding equal parts honey or rosewater. Diluted mixtures sting less than straight lemon juice.
Because lemon juice is a natural bleaching agent, it can lighten scars or other areas of hyperpigmentation. Try to keep the juice contained to just the scar as the acidic substance can cause irritation if used too broadly. Be careful not to touch your eyes or any open wounds, as lemon juice stings.
Because the lemon juice is acidic, it may cause skin to become excessively dry or to peel. In such a case, exfoliate the area gently and apply moisturizer.
The citric acid in lemon juice can make skin more sun sensitive, and sun can actually darken scars. For that reason, it's important to use sunscreen throughout this regimen.
Apply the lemon juice or juice mixture to affected areas once or twice daily for two weeks. If you are in a climate with intense sunshine, limit application to once per day. At the end of the two-week period, scars should have faded and become softer.