Hi dear , The symptoms you mention that is dry mouth can occur due to amny reasons like Side effect of medicine , inability of salivary glands to produce enough saliva , smoking and tobacco cgewing can produce symptoms like this . But in your case it seems to me that the medicine Restavit your are taking is the probable cause of dry mouth as one of its side effects . Other important reasons or dry mouth infection in oral cavity like gingivitis and diabetes . As you already gone through blod tests , they will help in ruling out such conditions . I would suggest you to consult your doctor and discus about dry mouth and your medicine . Doctor may alter the dose or prescribe substitute . For now keep yourself hydrate by drinking plenty of water , avoid fatty and sugary food and suck on sugar free candy . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari