What are the reasons for really smelly bowel movements in babies? My baby’s poop smells really bad!
My daughter is 7.5 months old, she is on Similac formula, Nestle rice cereal, and Heinz baby food, and her stool is green, mucousy like and it smells really strong. I have never known a baby (which I have been around a lot of) to have this strong smell to their stool.
I was just wondering if this is something to cause concern or if it is a side effect of either her food formula or teething.
Vanessa (B.C. Canada)
Reasons For Smelly Bowel Movements in Babies
The smell of babies’ stools can vary a lot just like with adults. Here are some possible reasons to consider when your baby’s poop smells really bad:
1. What they eat – What babies eat as well as their health will make the smell more or less strong. Breastfed babies often do not have strong smelling stools. A study from 2001 found that the stools of formula-fed babies contained a lot more odor-causing sulfur gases than breast milk poop. When a baby starts eating solid foods, the feces will change again; often to the worse when it comes to smell.
2. Lactose intolerance or some allergy can also lead to foul-smelling stools. So to test this, try to eliminate all cow’s milk from your baby’s diet and see if it helps.
3. Infections – In addition to these normal diet-related variations, the baby’s stools can also be affected by a stomach bug, a cold, or some food intolerance.
4. Rotavirus – A strong smell and very frequent pooping can indicate Rotavirus, regardless of poop color. Rota virus has other symptoms too, like fever, nausea and belly cramps, and young babies often become very sick from this virus. Since you don’t say that your baby is ill, this virus is most likely not the reason for her smelly poop.
5. Lactose overload – Green poop, a strong smell, and gas can be due to lactose overload, something that can happen if breastfeeding mom has an oversupply. Now, since you are not breastfeeding, this is not relevant for you right now. Did you breastfeed before? Oversupply can actually also lead to traces of blood in the poop.
6. Teething – An unexpected reason (at least it was for me) – is that the baby is teething. Despite a complete lack of research studies on this, many parents agree that their babies’ stools suddenly smelled like vinegar just before one of their baby’s teeth popped.
A sudden shift in the smell, and especially if combined with a change in consistency to the worse (diarrhea, gas, or mucus for example) often indicates that something is wrong.
In addition to watching your baby for other signs of illness or teething, you can also then think back on any new foods recently introduced, and take them away to see if it helps.
Since there are so many reasons for smelly bowel movements in babies, the best you can do as a parent is to look for other signs of teething as well as illness and also think back on any introduction of new foods or formula. If your baby seems to be ill, consult a doctor of course.
P.S. Here are two excellent reference books for baby health issues and injuries:
- My Child Is Sick!: Expert Advice for Managing Common Illnesses and Injuries
- Caring for Your Baby and Young Child by The American Academy of Pediatrics
More Baby Poop Issues
What’s your experience of smelly bowel movements in babies? Join the discussion! :-) Add your comments below or return to Baby Poop Q&A.