Some people may suffer from dry mouth, known as xerostomia, which can manifest with excessive thirst. It often occurs with aging and changes in hormone levels, and is treated by staying hydrated and avoiding things that can dry out your mouth more, says Finkelston, such as caffeine and alcohol. Certain medications can also cause dry mouth—antidepressants, blood pressure meds, and antihistamines are notorious for this side effect. “Dry mouth is sometimes associated with other medical conditions, but that can be ruled out relatively easily by your doctor,” says Finkelston. “More often it’s a nuisance, not an indicator of worsening illness.” Phew.