Reflux (Spitting Up) vs Pyloric Stenosis: Key Differences
Content reviewed against published AAP, AAP, NASPGHAN guidelines
Last reviewed:
Both reflux and pyloric stenosis cause vomiting in young infants. Normal reflux (spitting up) is very common and harmless, while pyloric stenosis is a surgical emergency requiring prompt diagnosis.
Key takeaways
- Projectile vomiting (forceful, travels several feet) is the hallmark of pyloric stenosis, not reflux
- Pyloric stenosis gets progressively worse over days/weeks; reflux stays relatively stable
- Babies with pyloric stenosis lose weight; babies with simple reflux gain weight normally
- Pyloric stenosis causes dehydration and fewer wet diapers; reflux does not
: What it is
Infant Reflux (GER/GERD): Stomach contents flow back up esophagus (immature valve)
Pyloric Stenosis: Thickened pylorus muscle blocks stomach outlet
: Typical onset
Infant Reflux (GER/GERD): First weeks of life; peaks at 4 months
Pyloric Stenosis: 2-8 weeks of age (usually 3-5 weeks)
: Vomiting type
Infant Reflux (GER/GERD): Effortless spitting up or mild vomiting
Pyloric Stenosis: Forceful PROJECTILE vomiting (shoots across room)
: Pattern
Infant Reflux (GER/GERD): Frequent small spit-ups throughout the day
Pyloric Stenosis: Progressively worsening; every feed, increasingly forceful
: Baby behavior after vomiting
Infant Reflux (GER/GERD): "Happy spitter" — comfortable, wants to feed again
Pyloric Stenosis: Immediately hungry again (hungry vomiter); increasingly distressed
: Weight gain
Infant Reflux (GER/GERD): Normal weight gain in most cases
Pyloric Stenosis: Weight loss or failure to gain — becomes dehydrated
: Vomit contents
Infant Reflux (GER/GERD): Curdled milk, sometimes slightly blood-tinged
Pyloric Stenosis: Non-bilious (no green/yellow bile); may have blood streaks
: Bowel movements
Infant Reflux (GER/GERD): Normal
Pyloric Stenosis: Fewer and smaller stools ("starvation stools")
: Treatment
Infant Reflux (GER/GERD): Positioning, smaller/frequent feeds; medication if severe
Pyloric Stenosis: Surgery (pyloromyotomy) — curative
: Demographics
Infant Reflux (GER/GERD): Equal in boys and girls
Pyloric Stenosis: 4-5x more common in firstborn males
| Infant Reflux (GER/GERD) | Pyloric Stenosis | |
|---|---|---|
| What it is | Stomach contents flow back up esophagus (immature valve) | Thickened pylorus muscle blocks stomach outlet |
| Typical onset | First weeks of life; peaks at 4 months | 2-8 weeks of age (usually 3-5 weeks) |
| Vomiting type | Effortless spitting up or mild vomiting | Forceful PROJECTILE vomiting (shoots across room) |
| Pattern | Frequent small spit-ups throughout the day | Progressively worsening; every feed, increasingly forceful |
| Baby behavior after vomiting | "Happy spitter" — comfortable, wants to feed again | Immediately hungry again (hungry vomiter); increasingly distressed |
| Weight gain | Normal weight gain in most cases | Weight loss or failure to gain — becomes dehydrated |
| Vomit contents | Curdled milk, sometimes slightly blood-tinged | Non-bilious (no green/yellow bile); may have blood streaks |
| Bowel movements | Normal | Fewer and smaller stools ("starvation stools") |
| Treatment | Positioning, smaller/frequent feeds; medication if severe | Surgery (pyloromyotomy) — curative |
| Demographics | Equal in boys and girls | 4-5x more common in firstborn males |
When to Worry
- Projectile vomiting (shoots 1-2 feet) in a baby aged 2-8 weeks — seek urgent evaluation
- Baby losing weight or not gaining weight appropriately
- Fewer wet diapers than expected (fewer than 6 per day) with vomiting
- Green (bilious) vomit — this is NEVER normal and requires emergency evaluation (may indicate bowel obstruction)
- Baby appears dehydrated: sunken fontanelle, dry mouth, lethargic
- Increasing frequency and force of vomiting over days
Frequently asked questions
What is the main difference between Infant Reflux (GER/GERD) and Pyloric Stenosis?
How can I tell if my baby has Infant Reflux (GER/GERD) or Pyloric Stenosis?
When should I worry?
Sources
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Bottom line
Both Infant Reflux (GER/GERD) and Pyloric Stenosis are common in young children. The key differences in symptoms can help you identify what your child may have, but when in doubt, consult your pediatrician.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.