Yellowish saliva in the morning may be caused by excessive plaque, pus in the mouth, gastroesophageal reflux, etc. It is recommended to go to the hospital for specific examination and treatment. 1. Often do not brush your teeth properly, there may be plaque, calculus overweight performance, poor oral hygiene, in the morning when brushing teeth will have bleeding gums, yellow saliva or even odor performance. 2. Peri-coronary abscess, periodontal abscess, apical abscess and other pus in the mouth, which may be mixed with saliva in the morning. 3. Gastritis, gastroesophageal reflux patients may appear reflux acidic liquid flow into the mouth symptoms, saliva will be yellow. Usually, attention should be paid to maintain oral hygiene and timely treatment of oral diseases and systemic diseases.