Hello, I can understand your concern. There are several causes that can result in loss of taste or metallic taste in mouth. Your mother s situation indicates two causes that can cause this effect. Firstly, if your mother is suffering from persistent sinus infection, it can result in sinusitis altering the taste perception. As she is already suffering from post nasal drip, sinusitis possibility should be considered. Visiting an ENT surgeon for the diagnosis based on physical examination of your mother. If that would be the reason, treating sinusitis will solve the trouble. In addition, hypertension medications often cause metallic taste in mouth. There is not much that can be done about it except your mother can chew flavored sugarless gums, brush teeth after meals, she can try different spices and foods, and drink lots of fluids. If it does not help, you can consult her cardiologist to find out if drug change is possible in her situation. I hope this information helps you. Thank you for trusting HCM for your concern. I wish your mother feels better soon! Best, Dr. Viraj Shah