Medicines that cause dry mouth are another cause of gum disease. This is because your body needs saliva to keep your mouth moist. Saliva also contains proteins that help protect your mouth from harmful bacteria. Examples of some medicines that can cause dry mouth are: medicines used to treat allergies, depression and high blood pressure. If you get dry mouth from taking medicines, there are steps you can take to keep the mouth moist and prevent gum disease. When bacteria infect your gums, gums and tissues around it swell. The swelling stretches the gum tissue allowing bacteria from your mouth and food to get through more easily. There are many tiny blood vessels in the gums around teeth that carry blood to and from your heart. The walls of these blood vessels also become stretched. So it is much easier for bacteria to enter these blood vessels in your gums and go into your blood when you have gum infection.