When you are run down and sick, your dental health may not be a high priority. You might be tempted to skip brushing your teeth a few times in the period of which you are ill.
In addition to this, it is usually difficult to breathe through your nose when you have a cold or flu, which can lead to you breathing through your mouth. As a result your mouth may become dry and have less saliva production. A dry mouth is more prone to decayed teeth.
Also the use of decongestants and antihistamines can all reduce your saliva production.
All of this combined is the perfect environment for a cavity to start.
It's best to try and drink lots of water and brush your teeth as you normally would. As hard as it might be, it's a time where it's even more important to keep your teeth clean.
