Reflux in babies: symptoms, treatment, and when to worry
Last updated September 3, 2026.
Reflux is when babies bring up milk during or shortly after feeds, and in most babies it is completely normal. Around half of all babies do it regularly because the muscle valve at the top of the stomach is still maturing. A baby who brings up milk but is happy, feeding well, and gaining weight needs no treatment at all, just a supply of muslin cloths. Reflux usually peaks around 4 months and resolves by 12 to 18 months.
When is it more than normal posseting?
Normal reflux: milky possets after feeds in a content, thriving baby. Reflux disease (GERD) is when reflux causes harm: poor weight gain, distress during and after feeds, back-arching and refusing feeds, or breathing problems. Those babies need assessment, because treatment exists and because some of those signs overlap with cow's milk protein allergy, which commonly coexists.
What actually helps?
- Feeding mechanics first: smaller, more frequent feeds, holding baby upright during and for 20 to 30 minutes after feeding, and winding regularly.
- Check the latch: a breastfeeding supporter or health visitor checking attachment reduces swallowed air, which reduces posseting.
- Never prop or thicken unsafely: do not raise the cot mattress or use sleep positioners; safe sleep guidance (flat, on the back) outranks reflux comfort.
- Feed thickeners when advised: for formula-fed babies with troublesome but uncomplicated reflux, a thickener can help, on professional advice.
- Medication for true GERD: acid-suppressing medicine is reserved for babies with reflux disease confirmed by assessment, not for happy posseters, and trials show it does nothing for crying alone.
- Tummy time while awake and watched: fine and helpful; sleep stays flat on the back regardless.
When is it an emergency?
Get same-day urgent care for green (bile-stained) vomit, blood in vomit, projectile vomiting after every feed (which suggests pyloric stenosis, a different condition), refusal to feed, fewer wet nappies, or a floppy, lethargic baby. Breathing difficulties, color change, or choking episodes with feeds are an emergency department visit. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Is it normal for my baby to spit up after every feed?
Yes, for most babies. Around half of all infants bring up milk regularly because the valve at the top of the stomach matures over the first year. The test is the baby, not the laundry: content, feeding well, gaining weight, plenty of wet nappies. That baby is a happy posseter and needs no treatment. Distress, poor growth, or refusing feeds is a different picture, and worth a review.
What is the difference between reflux and reflux disease?
Reflux is the mechanics: milk coming back up, which is normal. Reflux disease (GERD) is when that reflux causes harm: feeding refusal and back-arching, poor weight gain, significant distress, or breathing complications. The distinction matters because happy posseters need nothing, while GERD babies benefit from assessment and sometimes treatment, and some turn out to have cow's milk protein allergy instead or as well.
Should I raise the cot mattress to help my baby's reflux?
No. Raising the mattress, using wedges, or propping baby to sleep are not recommended: they are not proven to help reflux and they conflict with safe sleep guidance, which is flat, on the back, in a clear cot. The safe-sleep rules outrank reflux comfort every time. Upright holding after feeds, while awake and supervised, is the safe version of the same instinct.
Do anti-acid medicines help a crying, posseting baby?
Evidence says no for crying and posseting alone: trials show acid suppressors do not reduce irritability or regurgitation in otherwise thriving babies. They have a real role in confirmed reflux disease, decided after assessment. Overuse matters because these medicines are not side-effect-free in infants, so the trend is toward feeding-mechanics first and medication only for the babies who genuinely have GERD.
Could my baby's reflux actually be a milk allergy?
Possibly. Cow's milk protein allergy commonly causes vomiting and reflux-type symptoms, often with company: eczema, blood or mucus in stools, poor weight gain, or unusual fussiness. Reflux alone in a thriving baby rarely needs an allergy workup; reflux with those other features does. A health visitor or GP can trial a cow's-milk-free approach properly, with the right formula if needed.
When will my baby stop posseting?
Reflux typically peaks around 4 months and fades as the valve matures, sitting up begins, and solids arrive, resolving in most babies by 12 to 18 months. Persistent, worsening, or newly starting vomiting past that age deserves a review, because the natural history should be downhill by then. Until it resolves, the management is muslin cloths and the reassurance that growth is what counts.