Your teeth can change color for various reasons, such as: 1. Food and drink: beverages like tea, coffee, and wine, are major staining agents, as they all contain intense color pigments called chromogens that attach to the enamel, or the outer layer of the tooth. 2. Trauma: Being hit in the mouth may cause damage tooth structures, and may cause the more dentin (second layer of the tooth) to be formed, which is a yellowish color. 3. Tobacco: Tar and nicotine create big stains. Nicotine is colorless unless exposed to oxygen, in which then it turn into a yellowish color. 4. Age: As you age your enamel may wear and get thinner, revealing the dentin layer, which is yellow. 5. Medications: High blood pressure medications, antihistamines, as well as antipsychotics can all cause tooth discoloration. Children who were exposed to tetracycline or doxycycline while their teeth were developing (either in the womb or as an infant) may have discolored teeth later in life. Chemotherapy can also contribute to color changes.