Yellowish underarms may be related to dietary factors, color sweating, hyperhidrosis, axillary lichen planus, liver and gallbladder diseases and other factors. 1. Dietary factors: short-term yellowing of the underarm color, you need to know whether it is related to dietary factors, such as eating too many oranges and carrots, yellow sweat may appear, resulting in yellowing of the underarms. 2. Color Sweat Disorder: Color Sweat Disorder refers to the appearance of colored sweat in the armpits, usually patients will be accompanied by symptoms of armpit odor. Mild patients should pay attention to personal hygiene, if the symptoms are obvious, it is recommended to go to the hospital for treatment. 3. Hyperhidrosis: the skin in the armpit area is relatively thin and tender, often a lot of exercise leads to increased sweating, and the local friction stimulation during exercise may lead to local yellowing and redness. 4. Axillary lichen planus: Axillary lichen planus is a superficial infectious disease of axillary and pubic hair caused by Corynebacterium ciliatum, which may lead to color change of sweat, and may lead to yellowing of the armpits or staining of clothes. 5. Liver and gallbladder diseases: Patients with liver and gallbladder diseases, such as cholestasis, hepatitis, and bile duct stones, may develop yellow sweat patches. In addition to this, it is also important to know whether it is related to the staining of clothing. It is recommended to pay attention to personal hygiene, pay attention to dietary adjustments, and if necessary, go to the hospital for examination to understand whether it is related to pathological factors.