What causes purple discoloration at the edges of the lips?

　　In general, purple discoloration around the lip edges may be caused by emotional stress, food staining, cheilitis (lip inflammation), anemia, heart failure, or other reasons. If discomfort occurs, timely medical consultation is recommended. Detailed analysis is as follows:

　　1. Emotional Stress

　　When a person experiences intense emotional states such as extreme tension or excitement, the sympathetic nervous system becomes stimulated, causing vasoconstriction, especially in peripheral blood vessels. The altered blood flow following vasoconstriction in the lip area may cause purple discoloration. Learning to regulate emotions through deep breathing, meditation, and other methods can help alleviate such emotional stress.

　　2. Food Staining

　　Consuming foods rich in purple pigments, such as mulberries and purple grapes, may leave pigment residue around the lip edges, making them appear purple. Rinsing the mouth and cleaning the lips and oral cavity promptly after consuming such foods can help prevent this condition.

　　3. Cheilitis (Lip Inflammation)

　　Cheilitis is often caused by factors such as allergies, infections, or sun exposure. Inflammatory stimulation leads to local circulatory disturbances in the lips, changes in vascular permeability, leakage of certain blood components, and the effects of inflammatory mediators on blood vessels, resulting in purple discoloration of the lip edges. Symptoms such as redness, swelling, and itching of the lips may also occur. Patients can use medications such as Triamcinolone and Econazole Nitrate Cream, Delan Cream, or Chlorpheniramine Maleate Tablets according to medical advice.

　　4. Anemia

　　Anemia occurs due to lack of hematopoietic substances, impaired hematopoietic function, or blood loss, potentially leading to reduced red blood cells or hemoglobin in the blood. This results in decreased oxygen-carrying capacity, causing insufficient oxygen supply to areas such as the lip edges, leading to purple discoloration. Symptoms such as pallor and dizziness may also occur. Under a doctor's guidance, patients may use medications such as Ferrous Sulfate Tablets, Ferrous Fumarate Granules, and Folic Acid Tablets.

　　5. Heart Failure

　　Heart failure may be related to myocardial disease, excessive cardiac load, and other factors. It leads to impaired cardiac contraction or diastolic function, reduced cardiac output, systemic and pulmonary congestion, impaired blood return, and tissue hypoxia, causing purple discoloration of the lip edges. Symptoms such as dyspnea and fatigue may also accompany the condition. Patients can use medications such as Digoxin Tablets, Deslanoside Injection, and Furosemide Tablets as recommended by a physician.

　　In daily life, maintaining regular作息 (作息 should be translated as "作息" here, but since it's not translatable directly, it could be replaced with "routine"), ensuring adequate sleep, and enhancing physical immunity are important. Also, avoid prolonged stays in hypoxic environments such as high altitudes to reduce adverse effects on the body.