It is not very clear from your question why your lips may be changing into two different colors. A more detailed description of the symptoms would be necessary to ascertain the exact cause of your changing lip color. Usually, pale pink lips signify anemia or malnutrition. On the other hand, black lips can be a symptom that accompanies several other problems - irregular bowel movements, constipation, insomnia, and smoking. Sometimes, excessive intake of caffeinated drinks (like tea or coffee) and sunburn can also make your lips black. It is not unusual to have pale or dark lips at some point or the other. However, your case does seem quite unlikely as both these changes are happening at the same time. For a detailed diagnosis and treatment of your condition, you may want to consult a dermatologist.
Meanwhile, here are a few home remedies that you can try out to deal with your dry and cracked lips. Use a protective lip balm that keeps your lips appropriately moisturized. You can use petroleum jelly, glycerin, aloe vera gel, and vitamin E oil on your lips to keep them from getting dry. Do not frequently wet your lips with saliva as it exacerbates dryness of the lips. To exfoliate the dry skin on your lips, apply a mixture of glycerin and lemon juice on your lips and leave it overnight. You should also drink plenty of water and take care of your diet. Eat plenty of vegetables and fruits, whole grains, and nuts so that you get proper nutrition. A proper diet should also help you get back your natural lip color. Also, take care to protect your lips from sunlight and dry weather conditions. Preferably, carry a lip balm whenever you go out and apply it on your lips whenever your lips start to feel dry.
If your lips are turning pale due to anemia, you should also include iron-rich foods in your diet. Eat meat, poultry, fish, beans, lentils, broccoli, and tomato. Also, do avoid alcohol, caffeinated drinks, and preserved foods, as they are inhibitors of iron absorption.
All these home remedy methods described here should also help treat your dark lips. Additionally, you can apply lemon juice and other natural bleaches on your lips to help lighten the color of your lips. Give up smoking - if you do so, that is - because smoking is a major cause of lip discoloration. Also, do take some care to find out if the cosmetics you use are suitable for your skin; avoid anything that does not seem to go well with your lips.
answered by G R