The possible causes of yellow urine after waking up in the morning are: 1, the day before going to bed drinking special food or drugs, resulting in yellow urine coloring, such as riboflavin drugs and vitamin B complex drugs, after taking the phenomenon of yellow urine coloring, stop using the relevant drugs, drink more water, the urine color can gradually return to clear. 2, urine concentration, before going to bed drinking less water or sweating more, urine in the bladder for too long, such as More than 4 hours can appear urine concentration, concentrated urine out of the body can now be yellow urine. Only need to drink more water, more urination, urine color can turn clear. 3, urinary system infection or bleeding can lead to cloudy, yellow urine, or blood mixed in the urine appears brown or light brown, need to perform routine urine examination, if clear that there is an infection, antibacterial treatment gradually turn clear. 4, patients with obstructive jaundice, the urine in the direct bilirubin content is high, can appear yellow urine color. Treatment needs to cure obstructive jaundice, and their urine color will gradually turn back to clear.