According to traditional Chinese medicine, your mouth and lips belong to the element of earth, the Spleen and the Stomach (this also includes the digestive organs such as the intestines).
What do you see when you look at your mouth in the mirror?
The color of the lips corresponds to the blood flow and energy in the digestive organs, as well as the expression of your mood.
Pink, light red lips:
Normal lips are pink or light red in color, a sign of strength in the Spleen. This shows an even temperament. People with these lips can express themselves if they want to or not if they don't feel necessary. They can manage their mood and usually maintain consistency in their mood.
If the color of the lips is pale, this is a sign of a lack of blood flow and a lack of energy in the spleen (Qi or blood deficiency), or cold, which creates a mild sensitivity. Your digestion is probably weak, especially if you have a blood shortage, such as crying quickly and feeling offended easily.
Very red lips:
Redness indicates heat. The affected organ is often the stomach. There is fire locked up in the Spleen and heat in the Stomach. The Spleen is overactive and the person with this trait is usually very moody, thinks of someone who is explosive and quickly feels anger.
Dry, cracked lips:
Heat and dryness in the Stomach. There may also be other indicators of dehydration and/or heat in the body such as dry hands and feet, dry mucus in the nose.
Red and swollen gums: indicates Stomach fire. Think of heartburn as a symptom.
Bleeding gums: red and swollen gums mean that the fire of the stomach is damaging the blood vessels.
To give you a few other examples of what you can read from the mouth and lips:
Full, slightly swollen lower lip: too much moisture, usually in the intestines
Excessive saliva: too much fluid/mucus in the body
Tendency to cold sores/cold sores: damp heat
Blue, violet lips: cold or pain
Cracked corners of the mouth: may indicate a fungal infection