Chemotherapy and radiation treatment can cause dry mouth (also known as Xerostomia). Chemotherapy causes dry mouth by making saliva thicker, and thus more difficult for salivary glands to express. This symptom is usually temporary and clears up two to eight weeks after treatment ends.
Radiation treatment to the head, face or neck can also cause dry mouth. Because the salivary glands are more severely damaged by radiation, it make take several months for symptoms to clear up.
In the meantime, there are a few things you can do to treat dry mouth: