What causes xerostomia?

People get xerostomia when the glands in the mouth that make saliva are not working properly. Because of this, there might not be enough saliva to keep your mouth wet. There are several reasons why these glands (called salivary glands) might not work right.

Side effects of some medicines. More than 400 medicines can cause the salivary glands to make less saliva. Medicines for high blood pressure and depression often cause xerostomia.

Disease. Some diseases affect the salivary glands: Sjögren's Syndrome, HIV/AIDS, diabetes, depression and Parkinson's disease can all cause xerostomia.

Radiation therapy. The salivary glands can be damaged if they are exposed to radiation during cancer treatment.

Chemotherapy. Drugs used to treat cancer can make saliva thicker, causing the mouth to feel dry.

Nerve damage. Injury to the head or neck can damage the nerves that tell salivary glands to make saliva.

In addition, many cases of xerostomia are due to other causes not listed here, or may be of unknown origin (idiopathic).