Your baby is teething and has diarrhea. Both things are true. Neither is causing the other, and the second one is the one worth watching.
What teething does and does not touch
| Symptom | Caused by teething? | What the guidance says |
|---|---|---|
| Sore, swollen gums | Yes | The most common sign of all |
| Drooling, chewing, irritability | Yes | The three most reported |
| Rash in the dribble zone | Yes | Saliva on the skin, not the tooth |
| Diarrhea | No | Teething does not change how the gut works |
| Diaper rash | No | Teething does not make skin more sensitive below the waist |
| Fever of 38C or above | No | A fever is not explained by teething |
The short version.
- Teething does not reach the gut, so it cannot loosen stools
- Diarrhea for more than a day is a reason to call, whatever the gums are doing
- There is no color, smell or texture that marks stools as teething related, because the category does not exist
- Babies teethe for most of their first two or three years, so almost any illness overlaps with it
- Treating diarrhea as teething is how an infection gets waited out
- A baby with diarrhea and a fever needs advice, not a teething ring
Why teething does not reach the gut
This is the part that settles it, and it is worth more than a flat denial.
The published guidance does not just say diarrhea is unrelated. It gives the reason: teething does not change the way a baby's gut works. A tooth moves through gum tissue in the mouth. Nothing about that process touches the intestine, alters gut flora, or changes how food is absorbed. There is no mechanism to argue about.
The NHS reaches the same place from the other direction, noting that people think teething causes symptoms "such as diarrhoea, but there's no evidence to support this."
So this is not a case of two sides and a judgement call. It is one of the rare questions in infant health where the guidance is unanimous.
Then why does everybody believe it?
Because the timing makes it look true, and nothing in a parent's daily experience corrects the impression.
Teeth arrive on and off from the first tooth until the back molars, well into the third year. Across that stretch a baby is teething far more often than not. In the same window they start solid food, put everything within reach into their mouth, meet other children, and catch their first infections.
Two things that happen constantly will overlap constantly. Our brains read that overlap as cause, especially at 3am when we want an explanation that is not frightening. Teething is the comfortable answer. That is exactly why it is worth being careful with.
What color is teething diarrhea? What does it look like?
These questions come up a lot, and they all share a problem: they assume the category exists.
There is no color, consistency or smell that identifies stools as teething related, because teething is not producing them. Any description you find of what "teething diarrhea" looks like has been invented, and matching your baby against an invented description is worse than useless, because it can talk you out of calling someone.
What the stool looks like can still matter. It just tells you about your baby's gut, not about their teeth. Blood in it, or a baby who is unwell with it, is a reason to get advice today rather than a reason to inspect the gums.
How long does it last?
The honest version of this answer is that the question has the wrong subject.
There is no teething-related diarrhea to time. What there is, is diarrhea, and the guidance puts a clear limit on how long to watch it: because loose stools are a possible sign of infection, call your pediatrician if it lasts more than a day.
That is a usable rule and it does not depend on what is happening in your baby's mouth. One day. Then call.
Diarrhea with a fever
Two symptoms, neither of which teething explains, arriving together.
A temperature of 38C or 100.4F and above is a fever, and teething does not account for it either. Put the two together and you have a baby showing two signs of possible infection while a tooth happens to be coming through. The tooth is the least interesting thing in that picture.
That combination is on the published list of reasons to contact your provider. Do not wait the day out in this case.
What about diaper rash?
Also not teething, and the guidance is specific about why: teething does not make a baby's skin more sensitive, except possibly around the mouth. A sore bottom is a reaction to something else, often to the loose stools themselves sitting against the skin.
Worth separating clearly from the dribble rash around the mouth and chin, which genuinely is a teething side effect, because saliva causes it and saliva is something teething produces more of.
What teething actually causes
It is a real and uncomfortable thing, so it is worth saying what the evidence does support.
A 2016 meta-analysis of 16 studies covering 3,506 children found gingival irritation, irritability and drooling as the most frequent signs. A larger review in 2025 pooled 25 studies, put the overall prevalence of teething problems at 80%, and found increased biting and irritability the most common complaints.
Sore gums, chewing, dribbling, broken sleep and a generally fed-up baby. That is the real list. The gut is not on it.
When to call your pediatrician
Get in touch with your pediatrician or doctor if your baby has:
- Diarrhea lasting more than a day
- Diarrhea with a temperature of 38C or 100.4F or above
- Blood in the stool, or vomiting alongside it
- Fewer wet diapers than usual, or a baby who seems drowsy or hard to rouse
- A baby who seems unwell to you, whatever the thermometer and the gums say
This guide is general information, not medical advice. For your child's health or development, speak to your pediatrician or doctor.
Frequently asked questions
Can teething cause diarrhea?
No. Teething does not change the way a baby's gut works, so it cannot loosen stools. The NHS says plainly that there is no evidence for the belief. Loose stools during teething are a separate thing happening at the same time.
How long does teething diarrhea last?
There is no such thing to time. If your baby has diarrhea, the rule worth following is the published one: call your pediatrician if it lasts more than a day, because it is a possible sign of infection.
What color is teething diarrhea?
No color identifies it, because teething is not causing it. Descriptions you find of its color or smell are invented. Blood in the stool, or a baby who is unwell, is a reason to get advice regardless of color.
My baby has diarrhea and is teething. What do I do?
Treat the diarrhea on its own terms and set the teething aside. Keep fluids up, watch for fewer wet diapers, and call if it runs past a day or arrives with a fever, vomiting or blood.
Can teething cause diaper rash?
No. Teething does not make skin more sensitive below the waist. A sore bottom during teething is usually a reaction to something else, including loose stools against the skin.
Does teething cause a fever and diarrhea together?
Neither one. Both are on the list of reasons to contact your provider, and both arriving at once is a reason to call rather than to wait.
Sources
- Teething Pain Relief, American Academy of Pediatrics. Diarrhea listed as a false sign of teething, the reason given that teething does not change how the gut works, the instruction to call if it lasts more than a day, and the diaper-rash point.
- Baby teething symptoms, NHS. The wording that people think teething causes symptoms "such as diarrhoea, but there's no evidence to support this."
- Teething (Teething Syndrome), Cleveland Clinic. Diarrhea on the contact-your-provider list, alongside fever and vomiting.
- Massignan C, Cardoso M, Porporatti AL, et al. Signs and Symptoms of Primary Tooth Eruption: A Meta-analysis. Pediatrics. 2016;137(3):e20153501. Sixteen studies, 3,506 children, gingival irritation, irritability and drooling most frequent. doi:10.1542/peds.2015-3501.
- Garima J, Mathur VP, Tewari N, et al. Global prevalence of teething problems in infants and children, a systematic review and meta-analysis. International Journal of Paediatric Dentistry. 2025 May. Twenty-five studies, 80% overall prevalence, increased biting and irritability most common. doi:10.1111/ipd.13272.
Both reviews pool observational studies rather than trials. They are useful for showing which signs are commonly reported, not for proving which ones a tooth causes.
More from our teething cluster
- Can Teething Cause a Fever?. Where the line sits, and why the health bodies disagree about it.
- Teething Rash. Where a dribble rash appears, and why a rash on the body is not teething.
- When Do Infants Start Teething?. The 4 to 7 month window, and the order teeth arrive in.