GUIDE
No. Research does not support a direct link between teething and diarrhea. The timing overlap explains the association.
This myth is deeply entrenched — and understanding why it is wrong could prevent you from dismissing a real stomach bug as 'teething diarrhea.' Here is what the evidence shows and what to watch for.
The question of whether teething causes diarrhea has been studied directly in multiple well-designed research studies. The answer is consistent: no, teething does not cause diarrhea.
The landmark study by Macknin et al. (2000) tracked 125 infants prospectively, recording symptoms daily during tooth eruption periods and non-teething control periods. Diarrhea was not significantly associated with teething. The systematic review by Massignan et al. (2016), which pooled data from 16 studies, reached the same conclusion: diarrhea is not a reliable teething symptom.
This does not mean that your baby will never have loose stools while teething. It means that if your baby has diarrhea and also happens to be teething, the diarrhea has a different cause — and that cause may need attention.
| Study | Finding | Conclusion |
|---|---|---|
| Macknin et al. (2000) | Diarrhea (loose stools) was NOT significantly associated with teething in this prospective study of 125 infants with daily symptom tracking. | Diarrhea is not a teething symptom. |
| Wake et al. (2000) | Parents frequently attributed diarrhea to teething, but objective data collection did not support the association. | Parent perception of teething symptoms exceeds the objective evidence. |
| Massignan et al. (2016) | Systematic review of 16 studies found that diarrhea was NOT reliably associated with teething. Some individual studies found a weak association; the overall evidence did not support a causal link. | Diarrhea should not be attributed to teething. |
| Ramos-Jorge et al. (2011) | Prospective study found no statistically significant increase in diarrhea around tooth eruption. | Consistent with other studies — diarrhea is not a teething symptom. |
The association between teething and diarrhea is one of the oldest and most persistent myths in parenting. Grandparents believe it. Parent forums repeat it. Even some healthcare providers attribute loose stools to teething. The reason is not that the myth is true — it is that the timing overlap is nearly perfect.
Consider what is happening in a baby's life between 4 and 12 months:
They are teething. Teeth are moving through the gums, causing discomfort and the urge to chew on everything.
They are putting everything in their mouths. Babies at this age explore the world orally. They mouth toys, fingers, shopping cart handles, shoes, remote controls — anything they can reach. This is a massive source of pathogen exposure.
Their immune protection is declining. Maternal antibodies that provided passive immunity during early infancy are waning. Babies are now more susceptible to every virus and bacteria they encounter.
Many are in group childcare. Daycare is a petri dish for GI infections. Rotavirus, norovirus, and other stomach bugs circulate constantly.
They are starting solid foods. New foods can temporarily change stool consistency. What looks like diarrhea may actually be the gut adjusting to new inputs.
When all of this happens simultaneously — and it does, because the timing is identical — it creates a near-irresistible urge to connect the dots. The baby is teething. The baby has diarrhea. Therefore, teething caused the diarrhea. But the diarrhea was caused by the rotavirus from daycare, not the tooth.
| Factor | Explanation |
|---|---|
| Increased mouthing behavior | Teething babies put everything in their mouths to soothe gum discomfort. This dramatically increases their exposure to bacteria and viruses that cause GI illness. |
| Maternal antibody decline | Between 4 and 12 months, antibodies passed from mother during pregnancy begin to decline. Babies become more susceptible to infections — including GI infections — at the same time teething starts. |
| Daycare exposure | Many babies enter group childcare during the teething months. Norovirus, rotavirus, and other GI pathogens spread easily in daycare settings. |
| Introduction of solids | Solid food introduction (typically 4-6 months) coincides with early teething. New foods can cause temporary stool changes that parents may interpret as diarrhea. |
| Increased drool swallowing | Some experts have proposed that swallowing large amounts of saliva during teething may loosen stools. This has not been confirmed in research, and even if true, would not cause true watery diarrhea. |
One theory that circulates is that babies swallow large amounts of drool during teething, and this excess saliva loosens their stools. It is an intuitive idea, and it is occasionally mentioned by healthcare providers as a possible mechanism.
However, this theory has not been confirmed in controlled research. While it is true that teething babies drool more, the volume of drool that actually reaches the stomach (versus dripping down the chin) is modest relative to the baby's total fluid intake. And even if swallowed drool did slightly change stool consistency, it would not produce the kind of watery, frequent diarrhea that parents typically describe.
The bottom line: swallowed drool may contribute to very slightly softer stools in some babies, but it does not cause true diarrhea. If your baby has genuinely watery, frequent stools, the cause is almost certainly something they ingested or a virus they caught — not the drool.
You cannot spot diarrhea if you do not know what normal looks like. Logging diapers in tinylog gives you a clear picture of your baby's typical stool patterns, so when something changes, you can tell your pediatrician exactly what is different and when it started.
None of these symptoms should be attributed to teething. Every one of them warrants evaluation. The biggest risk with diarrhea in babies is dehydration, and young infants can dehydrate quickly.
Teething diarrhea is not a real diagnosis. When your pediatrician hears "my baby has teething diarrhea," they worry — not because of the diarrhea itself, but because they know the parent may not be taking it seriously enough. True diarrhea always has a cause, and that cause is not teething.
Track wet diapers during any diarrhea episode. This is the single most useful data point for assessing hydration. If your baby has at least 4-6 wet diapers in 24 hours, they are likely staying hydrated. Fewer than that warrants a call.
Continue feeding during diarrhea. The old advice to "rest the gut" or switch to a BRAT diet is outdated. Current guidelines recommend continuing normal feeding — breast milk, formula, and age-appropriate solids — during diarrheal illness. See our baby diarrhea guide for complete management guidance.
Do not use anti-diarrheal medications in babies. Over-the-counter anti-diarrheal products like Imodium are NOT safe for infants and young children. Diarrhea is the body's way of clearing an infection, and suppressing it can cause harm.
Some parents report that stools are slightly softer around teething episodes. Even if there is a minor effect from increased saliva or from chewing on random objects, this is different from true diarrhea — which means a significant increase in frequency and wateriness compared to your baby's baseline. If your baby's poop is slightly softer but they are having the same number of diapers and acting fine, that is not diarrhea.
You cannot identify diarrhea if you do not know what your baby's normal poop looks like. Breastfed baby poop is naturally loose, seedy, and frequent — that is normal, not diarrhea. Formula-fed poop is typically paste-like and less frequent. True diarrhea is a change from whatever your baby's normal pattern is.
Whether diarrhea is caused by a virus, bacteria, or anything else, the primary concern is dehydration — not the diarrhea itself. Track wet diapers carefully during any diarrhea episode. Continue breastfeeding or formula feeding to maintain hydration. If wet diaper count drops, call your pediatrician.
This is the real danger of the teething-diarrhea myth. A baby with watery diarrhea, fever, and reduced wet diapers needs medical evaluation. Dismissing these symptoms as teething can delay treatment for a GI infection that could lead to significant dehydration. When in doubt, call.
This guide is for informational purposes only and is not a substitute for professional medical advice. If your baby has a fever of 100.4°F (38°C) or higher, is refusing to eat, or seems unusually unwell, contact your pediatrician — these symptoms are not typical of teething alone.
