Several different factors cause inflammation of the tongue. The most common types of inflammation are those caused by viral and bacterial infections. A virus or bacteria in the mouth can cause the tongue to become inflamed, leading to a sore tongue. An infection caused by a fungus can also cause inflammation, although this type usually requires treatment with antifungal medications rather than antibiotics.
Infections caused by viruses generally have no symptoms until the tongue becomes tender and red. By contrast, bacterial infections often occur along with other symptoms, such as swelling of the throat or pain when swallowing.
While these are not typical symptoms of a sore tongue resulting from an inflammatory condition, they need to be investigated to ensure that an infection is not present. Some people report having foul-tasting liquids in their mouths when they wake up, but this is more likely to be a sleep apnea symptom than a sore tongue. If you are consistently waking up with a dry mouth and sore tongue, try making sure you drink enough water throughout the day.
Treatments for sore tongues caused by inflammation vary depending on the triggers and the possibility of a mouth infection. If there is an infection, your doctor may prescribe appropriate treatment.