According to Skin Care Guide, the acid found in lemon juice can help lighten the appearance of freckles. However, lemon juice is not a permanent solution for fading freckles. Typically, freckles reappear once the skin is exposed to sunlight.
Individuals who want to lighten freckles should apply fresh lemon juice directly to the area with freckles and allow the juice to sit for at least ten minutes before rinsing with cool water. Care2 recommends applying lemon juice to freckles at least once a week until the freckles fade. Rubbing a slice of lemon sprinkled with sugar on the face not only helps fade freckles, but also exfoliates the skin.