My child has evening breath. Is that the same as morning breath?

Dear Dr. Katz,

My 8-year-old son has been having a weird problem lately. I don't know if this is a real condition or not, but he keeps getting "evening breath." You know, like morning breath but later in the day, usually after school. As far as I can tell, it's not for lack of brushing (since I make sure he does that twice a day). Any thoughts? His friends are starting to notice, so anything you can recommend will be much appreciated!

Waiting To Inhale (Seattle, WA)

Dear WTI,

Thanks for writing! I can't guarantee that I'll definitely pinpoint the cause your son's bad breath, but let's give it a whirl. There are plenty of causes of evening breath (or morning breath in the evening, as you astutely put it), so any one of these could be to blame. Fortunately, some specialty breath fresheners will probably set this situation to rights in a jiffy.

When I first read your email, it seemed like there might not be enough information in it to make an informal diagnosis. However, on second glance, I believe I'm up to the task.

As you may know if you've been following these posts, nearly all halitosis is a byproduct of oral bacteria. Your mouth and your son's are host to billions of microscopic creatures, many of which are pretty harmless. But a few dozens strains are especially bad for your dental health and breath odor.

These species are anaerobic bacteria - that is, they're microbes that like a pretty dry environment. Now, as I'm sure you're aware, morning breath is caused by dry mouth, specifically by sleeping with your jaws agape. So is this the cause of your son's evening breath?

Unless he's sleeping in class, I doubt it. But the odor may still be coming from dry mouth, or even another secret source. Here are my educated guesses:

- Is your son a bit of a mouth breather? If so, that's almost definitely the cause of his evening breath.

- Does he practice sports after school? Vigorous exercise and heavy breathing can parch the mouth.

- Is he a nervous boy? Anxiety and nerves can leave the mouth dry (and the palms wet). Maybe school is stressing him out more than usual lately?

- Finally: I can think of no way to put this delicately, so I'll just ask. Might he have something stuck up his nose? Believe it or not, this can cause bad breath in kids. The National Institutes of Health even says so.

Regardless of the cause, a good, alcohol-free specialty mouth rinse at home (and some specialty breath freshening gum for school) should do the trick. Unless the problem was that last one...

Anyway, good luck!