The common causes of a large coffee-colored spot on the waist include hyperpigmentation, lichen planus, coffee spots, age spots, and melanosis, etc. It does not necessarily have an impact on health and needs to be analyzed specifically. 1. Hyperpigmentation: if the patient’s waist used to have dermatitis, eczema or herpes zoster, in the process of disease as well as in the process of recovery, pigment particles will be secreted, resulting in hyperpigmentation, which will not be accompanied by pain and itching symptoms. Hyperpigmentation has no effect on the patient’s health. 2. lichen planus: this is due to fungal infection of the skin with infectious lesions, manifested as painless and itchy brown plaques, there may be dandruff above the plaque. It will not jeopardize the health of patients, but it is not easy to cure, and there is a probability of recurrence. 3. Coffee spot: belonging to hereditary disease, there will be coffee-colored or brown plaques on the body, with smooth surface and no abnormal symptoms, which has little effect on the health of patients. 4. Age spots: related to skin aging, manifested as brown patches. Generally, it has little effect on health, but it needs to pay attention to the changes of the condition in time. 5. Melanosis: it belongs to a kind of pigmentation disease, which may be related to contact with photosensitive substances or long-term constipation, etc. It has a certain probability of malignant change. It is recommended that patients consult a doctor in time and strictly follow the medical advice to avoid delaying the condition.