Applying a small amount of lemon juice to your lips may help lighten dark pigmentation over time.
Placing cucumber slices on your lips might have a soothing and mildly lightening effect.
Aloe vera has various skin benefits and may help soothe and lighten pigmented areas.
Mixing honey and rose water into a paste and applying it to your lips could be another option.
Applying coconut oil to lips helps keep them moisturized and may contribute to a slight lightening effect.
Gently exfoliating your lips with a homemade scrub made of sugar and honey or olive oil might help remove dead skin cells.