Dry, damaged lips can have a dark appearance. Use a good quality lip balm. Check the ingredients to make sure that it has both a moisturizer, such as shea butter or cocoa butter, and a binding agent, such as beeswax.  Good moisturizing ingredients to look for include shea butter, cocoa butter, and almond oil. Shea butter has been used since ancient times and is known for its antioxidant and moisturizing properties. Cocoa butter is often used to reduce discoloration from scarring. Almond oil is considered one of the best oils to improve the health and appearance of skin. Protect your lips from the sun as you protect the rest of your skin. Lips don't tan but they can burn and become dry which will make them appear darker.  Make sure your lip balm has sun blocking material of SPF 20 or greater. Use lipsticks with sun block of SPF 20 also. , if you do. Smoking can discolor lips, as tobacco, nicotine, and tar can all darken lips. Additionally, heat from cigarettes may cause you to produce more melanin (which protects skin from the sun) and darken your lips. Quitting is hard. Talk to your doctor about medications that can help you quit, as well as gum or patches.

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Write a summary of the previous text in Vietnamese:
Dưỡng ẩm môi. Dùng kem chống nắng. Ngừng hút thuốc lá.