A taste of ammonia in the mouth can be caused by non-disease factors, or by pathologies such as oral disease, UTIs, or GI bleeding. 1. non-disease factors: such as smoking or food residue in the mouth, causing bacterial reproduction leading to halitosis, a smell of ammonia in the mouth, timely oral cleaning after meals can be. 2. Pathological factors. (1) oral diseases: such as periodontitis, dental caries and other causes of bad breath, can cause a mouth of ammonia odor, accompanied by pain. (2) uremia: due to renal dysfunction, resulting in the body’s metabolic waste can not be discharged in a timely manner, accumulated in the body, only through the respiratory tract, skin, etc. will be a small portion of the metabolic waste urea discharged, can be caused by ammonia taste in the mouth. (3) Gastrointestinal bleeding: especially the upper gastrointestinal bleeding, due to blood accumulation in the digestive tract for a long time, causing elevated urea absorption, resulting in hyperurinemia, which in turn manifests itself as an ammonia taste in the mouth. Long-term taste of ammonia in the mouth can not be relieved or even aggravated, it is recommended to go to the hospital in a timely manner to find out the cause of the taste of ammonia and follow the doctor’s instructions to avoid delays in the condition.