Causes

Dry mouth is caused when the salivary glands in the mouth don't make enough saliva to keep your mouth wet. These glands may not work properly as the result of:

• Medications. Hundreds of medications, including many over-the-counter drugs, produce dry mouth as a side effect. Among the more likely types to cause problems are some of the drugs used to treat depression, high blood pressure and anxiety, as well as some antihistamines, decongestants, muscle relaxants and pain medications.
• Aging. Many older people experience dry mouth as they age. Contributing factors include the use of certain medications, changes in the body's ability to process medication, inadequate nutrition, and having long-term health problems.
• Cancer therapy. Chemotherapy drugs can change the nature of saliva and the amount produced. This may be temporary, with normal salivary flow returning after treatment is completed. Radiation treatments to your head and neck can damage salivary glands, causing a marked decrease in saliva production. This may be temporary or permanent, depending on the radiation dose and area treated.
• Nerve damage. An injury or surgery that causes nerve damage to your head and neck area can result in dry mouth.
• Other health conditions. Dry mouth can be due to certain health conditions, such as diabetes, stroke, yeast infection (thrush) in your mouth or Alzheimer's disease, or due to autoimmune diseases, such as Sjogren's syndrome or HIV/AIDS. Snoring and breathing with your mouth open also can contribute to dry mouth.
• Tobacco and alcohol use. Drinking alcohol and smoking or chewing tobacco can increase dry mouth symptoms.
• Recreational drug use. Methamphetamine use can cause severe dry mouth and damage to teeth, a condition also known as "meth mouth." Marijuana also can cause dry mouth.