Reflux: what's normal, what's not

Reflux in babies is one of the most common, most over-treated, and most anxiety-producing things in the first year. This article walks through the distinction between physiological reflux — nearly universal in infants — and GORD (gastro-oesophageal reflux disease), which affects a much smaller number of babies and genuinely warrants medical intervention.

What reflux actually is

Gastro-oesophageal reflux is the movement of stomach contents back up into the oesophagus. In babies, the muscle at the top of the stomach (the lower oesophageal sphincter) is immature and short, the oesophagus is short, and the stomach is small and filled with liquid. The result: reflux is near-universal, most feeds bring a bit back up, and it is not dysfunction — it is infant anatomy.

About 40–50% of babies reflux at least daily in the first three months. By 6 months, most have significantly improved. By 12–18 months, the majority have grown out of it entirely. Reflux that persists past 18 months warrants paediatric review.

Happy spitters vs unhappy babies

Paediatricians use a useful distinction: the happy spitter versus the unhappy refluxer. Both are common. Only one needs treatment.

Happy spitters

• Reflux visibly — milk comes back up, sometimes at volume.
• Feed well.
• Gain weight appropriately.
• Are content between feeds.
• Create laundry.

Happy spitters do not need medication, investigation, or formula change. They need more muslins. Reassurance is the treatment.

Unhappy refluxers (possible GORD)

• Persistent irritability, especially after feeds.
• Back-arching, writhing during or after feeds.
• Feed refusal or fussing at the breast/bottle that develops over weeks.
• Poor weight gain or weight loss.
• Vomiting that is forceful, green-tinged, or blood-streaked.
• Persistent cough, wheeze, or apnoea.
• Waking frequently, screaming, unable to settle back.
• Ear infections or hoarseness.

If several of these are present, the reflux may be causing real discomfort and is worth investigating.

What makes it better (for all refluxers)

• Smaller, more frequent feeds. An overstuffed stomach empties more slowly and refluxes more.
• Upright after feeds — 20–30 minutes. Gravity is your friend.
• Winding mid-feed and at the end. Trapped air in the stomach displaces milk upward.
• Paced bottle feeding if bottle-fed — slower flow teats, baby upright.
• Avoid tight clothing or nappies that compress the abdomen.
• For reflux that is sleep-disruptive: a slightly raised cot mattress (always with the incline under the mattress, never pillows) may be discussed with a clinician, but the safe-sleep rule of flat mattress generally holds unless specifically advised by a paediatrician.

What does not help as much as parents hope

Formula changes

For most refluxers, changing formula is not the answer. Cow's milk protein intolerance can mimic reflux and does warrant a hydrolysed or extensively-hydrolysed formula under medical guidance — but this is different from a standard formula switch. Moving between brands of the same type of formula rarely changes anything.

Thickeners

Anti-reflux formulas or added thickeners reduce visible spit-up but do not reduce actual acid reflux and can cause constipation. They are a cosmetic fix for the laundry, not a treatment for the baby's discomfort.

Over-the-counter acid suppressors

Do not give infants any medication without a GP. Antacids and acid suppressors are over-prescribed in babies — most research shows limited benefit for mild-to-moderate reflux in infants, and potential downsides including increased infection risk. Prescription is a GP or paediatrician decision, not a pharmacy one.

When to see your GP

• Weight gain is poor, stalled, or going backwards.
• Feeding is being refused or cut short by distress.
• Your baby is persistently uncomfortable, crying for extended periods, and sleep is severely disrupted.
• Vomiting is forceful (projectile), recurring, or bloody.
• Green vomit at any age — this is a surgical red flag, not a reflux one.
• Symptoms are new or worsening after 6 months.

Cow's milk protein intolerance — the mimic

Cow's milk protein intolerance (CMPI) affects 2–5% of infants and can present with symptoms that look like severe reflux — irritability, poor feeding, back-arching, vomiting — along with other features: diarrhoea or constipation, blood or mucus in stool, eczema, and failure to thrive.

CMPI is usually diagnosed through an elimination trial under GP or paediatric supervision — either a maternal dairy-elimination diet if breastfeeding, or a switch to an extensively hydrolysed formula if formula-feeding. Improvement in 2–4 weeks is the diagnostic signal. Do not start an elimination diet without clinical guidance — nutritional adequacy is the reason.

The timeline parents should have in their head

Reflux typically:

• Peaks between 2 and 4 months.
• Starts improving noticeably around 4–6 months as the sphincter matures and the baby spends more time upright.
• Mostly resolves by 12 months.
• Almost always resolved by 18 months.

Knowing this trajectory is calming. Most of reflux is a waiting game the baby wins. For the small number of babies with GORD, the right investigation makes the remaining months bearable.

Reflux is messy and loud and your living room smells like milk curd. For most babies, that is all it is. For the rest, there is a clinical pathway that does not start with a formula swap and does not end with indefinite medication. Your GP is the right first door.