Dry mouth and dry nose may be caused by dry syndrome, or it may be caused by hypertonic dehydration, or it may be caused by heat stroke. 1. Dry syndrome: Dry syndrome is a chronic inflammatory autoimmune disease that involves a variety of exocrine glands. As the exocrine glands become less functional, patients may experience dry mouth and nose, as well as dry eyes, dry skin and muscle pain. 2. Hypertonic dehydration: Hypertonic dehydration is a kind of disease caused by the reduction of extracellular fluid due to insufficient water intake or large amount of water loss, and the patients may also have the symptoms of dry mouth and nose, and the serious patients may also have the symptoms of restlessness, fainting, and so on. 3. Heatstroke: heatstroke is a disease caused by dysfunction of the thermoregulatory center, sweat gland failure and excessive loss of water and electrolytes, patients with this disease will also have symptoms of dry mouth and nose, and patients can also experience high fever, headache, coma and other symptoms. If the symptoms of dry mouth and nose persist without relief, the patient should consult a doctor to identify the cause and dispose of it.