Cancer therapy—particularly radiation therapy to the head and neck and certain chemotherapy drugs—can cause dry mouth (xerostomia) by damaging the salivary glands or interfering with the body's ability to produce saliva. Here’s how each type of treatment contributes:

1. Radiation Therapy (especially to head/neck):

• Direct damage to salivary glands: Radiation can injure or destroy the salivary gland tissue, especially the parotid, submandibular, and sublingual glands, reducing or completely stopping saliva production.

• Long-term or permanent effects: Damage can be long-lasting, and saliva flow might not fully return even after therapy ends.

• Onset: Often begins during the second or third week of radiation and worsens as treatment continues.

2. Chemotherapy:

• Systemic effects on salivary flow: Chemotherapy drugs can cause inflammation or changes in the mucous membranes (mucositis), leading to temporary reductions in saliva production.

• Effect on fluid balance: Chemo may cause dehydration and fluid loss, reducing saliva as a secondary effect.

• Taste and appetite changes: These can further contribute to reduced oral intake and symptoms associated with dry mouth.

3. Other contributing factors:

• Medications used during cancer treatment (like opioids, anti-nausea meds, antidepressants, etc.) often have dry mouth as a side effect.

• Mouth breathing or oxygen therapy during hospitalization may also exacerbate dryness.

Why it matters:

Dry mouth affects speech, taste, swallowing, and oral hygiene, increasing the risk for:

• Cavities and root caries

• Oral infections (like candidiasis)

• Gum disease

• Discomfort and nutritional issues