Does Stress Cause Bad Breath?What Studies Show

A big presentation, a hard week, a first date: many women feel their breath gets worse when they’re on edge. A few studies have tested whether stress changes the sulfur gases that make breath smell, and whether stressed people worry about their breath more.

Exam day and the premenstrual week

Researchers in Brazil looked at two kinds of stress.¹

• An exam. In 71 dental students, sulfur gases in mouth air were measured a week before a biochemistry exam, on exam day and a week after. On exam day the gases rose and saliva flow fell.¹
• PMS. In 50 women, those with premenstrual syndrome had higher sulfur gases in the premenstrual week than women without it, though their saliva flow wasn’t clearly different.¹

The authors suggested stress may raise these gases, but that less saliva doesn’t explain it all.¹ See does bad breath change with your period?

A stress test in the lab

A later study from the same university gave volunteers a color-word test on video, used to create short-term stress.²

• Total sulfur gases and hydrogen sulfide rose in both men and women.²
• Women had higher levels than men.²

Feeling stressed, feeling smelly

An Iranian survey asked 4,763 adults, over half of them women, about their breath and their mood.³ About 53% thought they had bad breath.³ Those who did were more likely to be:

	Odds compared with others
Anxious	About 1.8 times3
Stressed	About 1.4 times3
Depressed	About 1.3 times3

This survey measured how people judged their own breath, not how it smelled to anyone else.³ So it can’t separate stress changing breath from stress making people worry about it.

How to read this

The lab studies measured sulfur gases rather than how breath smelled to another person, and they were small. Together they suggest stress may shift breath a little for a short time. They don’t show stress as a main cause of lasting bad breath.

UK health advice lists dry mouth among the causes of bad breath, and the everyday fixes are the same whether you’re stressed or not:⁴

1. Brush twice a day for 2 minutes with fluoride toothpaste.
2. Clean your tongue once a day. See how to use a tongue scraper.
3. Clean between your teeth once a day.
4. Sugar-free gum or mints can help after strong-smelling food.

When it’s worth a check

See a dentist if bad breath lasts after a few weeks of good cleaning, or if your gums are painful, bleeding or swollen.⁴ If you’re sure your breath smells but others say it doesn’t, see worried about bad breath others can’t smell and how to tell if your breath smells.

Try: “My breath seems worse when I’m stressed, and my mouth goes dry before meetings. Could you check my gums and tongue, and is there anything that helps with dry mouth?”

Is It My Breath? covers this in Chapter 10, “The Worry Loop,” in a section called “Breaking the Loop.” Its Breath Log takes one line a day for time, food, dryness, taste and what you tried, so you can see whether stressful days line up with worse breath. See the book.