Your mouth can get dry if you snore or sleep with it open, and that makes it an even better home to the bacteria that cause “morning breath.” You’re more likely to snore if you sleep on your back, so it can help to sleep on your side. Food in your teeth also can help bacteria grow — a good brush and floss before bed can cut down on that.
If your breath has a metallic smell, you might have bacteria growing under your gum line — that can lead to inflammation and even infection. Your dentist might call it periodontitis. You’re more likely to have it if you smoke or don’t brush and floss regularly. Gum disease also can run in families.
This condition makes stomach acid flow the wrong way, back into the tube that connects your throat to your stomach (your esophagus). It can give your breath a sour smell and bring up bits of food or liquid into your mouth. The acid also can damage your throat and mouth, and that can make a breeding ground for more smelly bacteria.