Most importantly, cut back on smoking, consuming any tobacco-based products to prevent lip pigmentation. Apply a lip balm with SPF to protect your lips from sun damage. Lip products with active ingredients like retinol and kojic acid can help lighten your lips. You can make use of honey, beetroot juice or olive oil as an overnight treatment on your lips to reduce pigmentation. Making an at-home lip mask using strawberries or raspberries mixed with aloe vera (applied for 10 mins and washed off) can also help lighten your lips.