Hi Dear, Welcome to HCM. Understanding your concern. As per your query dark marks on the lips due to due excessive licking of lips along is because it remove the natural moist layer from the lips .Hence cracks starts appearing on the lips which further become prone to fungal infection and other major reason is hyper pigmentation which is generally caused by excessive exposure to the UV rays. Need not to panic. I would suggest you to start use petroleum jelly , drink lots of water ,avoid to stay in dry environment for longer period . Avoid using creams containing high steroid content ,wash your face with mild soap twice a day and avoid licking your lips . Use lip balm which can be directly applied rather than if you use finger it will cause spreading of infection again and again whenever you will apply with finger. As far as hyper pigmentation is concern avoid exposure to UV , cover your face while going outside or use crems with SPF factor. Take healthy diet green vegetables and fruits containing lots of vitamins play miraculous role in treating hyper pigmentation. Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari