Bad breath, also known as halitosis, can be embarrassing and uncomfortable. It can also be a sign of an underlying dental or medical condition. There are a few different symptoms that can indicate bad breath. Foul odour coming from your mouth. This is the most obvious sign of bad breath. Dry mouth. A dry mouth occurs when there is not enough saliva to keep the mouth moist. This can be due to medications, medical conditions, or simply not drinking enough water. White coating on your tongue. This is indicative of plaque build-up on your tongue. Plaque is a biofilm made of food debris and bacteria. Bad, sour or metallic taste. This is most often observed in the morning as the patient wakes up. It is particularly seen in patients wherein the cause of bad breath is gum disease, acid reflux or a sinus infection. If you are concerned about your breath, it is best to consult with your dentist or primary care physician. They can determine the underlying cause of your bad breath and recommend treatment.