What could be the cause of dry mouth and dry tongue?

Many causes: If the dryness is new, it may be dehydration, a medication side effect, or part of an infection. If it lasts longer, work-up would consider the above options as well as others, such as a possible auto-immune or thyroid issue, or other problems. If it persists, see your doctor.

Dry mouth: Dry mouth can be caused by; medications, smoking, chemotherapy, radiation therapy, etc.. Do you have decay by the gums of your teeth? That could indicate there is dry mouth. Ask your physician and dentist to evaluate. You may need a strong Fluoride rinse prescription.

Use of marijuana can also cause an extremely dry mouth. Regardless of the cause a new treatment involves the use of a baking soda-xylitol night gel inside a protective retainer. This has the promise of reducing decay rates for sufferers.

Causes include, but are not limited to: Smoking (anything), alcohol, viral/bacterial/fungal infection, narrow upper jaw, enlarged tonsils/adenoids, a number of systemic Sjogren's Syndrome, small airway volume, various prescription/OTC/recreational drugs, allergies, obesity, astringent foods, diminished or blocked nasal airway, and so many other possibilities. See both Dentist & Physician.