What is reflux in babies?

Written by Yuppo Lab Experts.

Updated 27 October 2026

Reflux is when milk comes back up from a baby's stomach into the food pipe and mouth, often as spit-up after feeds. It is very common because the muscle at the top of the stomach is still developing; according to the NHS, it usually starts before 8 weeks and gets better by age 1.

Key takeaways

  • Most babies with reflux are happy and gaining weight.
  • Babies should always sleep flat on their back, even with reflux.
  • Raising the head of the cot is not recommended.

What you can do

  • Keep your baby upright during and after feeds.
  • Burp your baby regularly during feeds.
  • Offer smaller, more frequent feeds.

When to talk to your doctor

See your doctor if reflux starts after 6 months, continues after age 1, or your baby is not gaining weight. Get urgent help if your baby vomits green or yellow fluid or blood, vomits forcefully, has blood in their poo, refuses feeds or seems very distressed.

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