Dry mouth, also known as xerostomia, occurs when the salivary glands do not produce enough saliva to keep the mouth moist. The causes of dry mouth include:

• Medications: Hundreds of prescription and over-the-counter drugs can reduce saliva production. Common culprits include medicines for depression, high blood pressure, anxiety, allergies (antihistamines), decongestants, muscle relaxants, pain relievers, and some Parkinson’s disease drugs

• Dehydration: Not drinking enough fluids, excessive sweating, illness, or medical conditions causing fluid loss (like blood loss or chronic diarrhea) can lead to thick saliva and dry mouth

• Aging: Older adults often experience dry mouth due to changes in how the body processes medications, poor nutrition, and long-term health problems

• Cancer treatments: Chemotherapy can alter saliva quantity and quality temporarily, while radiation therapy to the head and neck can damage salivary glands, potentially causing lasting dry mouth

• Nerve damage: Injury or surgery affecting nerves in the head and neck can impair signals to salivary glands, reducing saliva production

• Medical conditions: Diseases such as Sjögren’s syndrome (an autoimmune disorder), diabetes, stroke, Alzheimer’s disease, HIV/AIDS, mumps, and others can cause dry mouth

• Other causes: Salivary duct blockages, infections of the salivary glands, hormone changes (pregnancy or menopause), tobacco use, and habitual mouth breathing due to nasal congestion may also contribute

In summary, dry mouth results from reduced saliva production due to medication side effects, dehydration, aging, cancer therapies, nerve damage, or underlying health conditions