RecruitingPhase IVInterventional

Omeprazole for babies born early or full-term, who are experiencing reflux

Many babies bring up milk after feeding, but some have severe reflux that causes pain, constant crying, and poor weight gain. Doctors often prescribe a medicine called omeprazole to reduce stomach acid. However, there is little strong evidence proving how well it works or its long-term safety in infants. The OTTER study is testing omeprazole against a dummy medicine (placebo) in babies under six months old who have troublesome reflux. Half of the babies will receive omeprazole liquid for four weeks, and half will receive the placebo. Neither parents nor doctors will know which treatment the baby gets. Families will receive regular support phone calls and complete short online questionnaires over six months. The results will help doctors understand whether omeprazole is safe and helpful, helping to guide future NHS treatment for babies.

At a glance

Status

Recruiting

Phase

Phase IV

Sponsor

University Hospital Southampton NHS Foundation Trust

Enrolment target

500

Start

30 Jul 2026

Estimated completion

29 Feb 2028

Gastro-oesophageal reflux

What is this study about?

Many young babies bring up milk after feeds. This is called gastro-oesophageal reflux, or simply reflux. For most infants, it is mild and improves naturally as they grow. However, for some babies, stomach acid travels up into the food pipe and causes severe pain, distress, and problems with gaining weight. Seeing your baby in pain can be an exhausting and upsetting experience for any parent.

When simple changes—such as keeping the baby upright after feeds or using milk thickeners—do not help, doctors often prescribe a medicine called omeprazole. Omeprazole lowers the amount of acid the stomach produces. Even though it is widely used across the UK, we do not have clear proof showing whether it genuinely relieves symptoms in babies, or whether it might cause long-term problems such as tummy bugs or weaker bones.

The OTTER clinical trial aims to find clear answers. Run by the University of Nottingham and funded by the National Institute for Health and Care Research (NIHR), this study compares omeprazole directly with a dummy medicine (a placebo). The findings will help doctors know whether omeprazole is truly worth prescribing, ensuring future NHS care is safe, effective, and evidence-based.

Key takeaways

Investigates whether omeprazole is truly safe and effective for treating severe baby reflux.
Open to babies under six months old (corrected age for premature babies) with diagnosed reflux.
Babies receive either omeprazole or a dummy liquid for four weeks.
Includes check-ins and simple online questionnaires over a six-month follow-up period.
Funded by the National Institute for Health and Care Research (NIHR) to help shape NHS guidelines.

Who may be eligible?

This study is open to babies under six months old who have been diagnosed with troublesome acid reflux by a doctor or paediatrician. If your baby was born early (prematurely), their age is calculated from their original due date. To take part, your baby must be taking full milk feeds, and standard first-step options (such as milk thickeners or infant Gaviscon) must have already been tried or considered unsuitable by your doctor.

Babies cannot join the trial if they have had surgery on their stomach, food pipe, or bowel, or if they have serious nerve conditions that affect feeding. Babies who have taken omeprazole or any similar acid-reducing medicines in the past two weeks are also unable to take part.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

My baby is under 6 months old (or under 6 months past their due date if born premature).
A healthcare professional has diagnosed my baby with severe or troublesome reflux.
My baby is on full milk feeds.
We have already tried milk thickeners or alginates, or our doctor advised they were unsuitable.
My baby has not had omeprazole or similar acid medicines in the last two weeks.
My baby has not had major surgery on their stomach, food pipe, or bowel.

Answer every question to see your result.

What does participation involve?

If you decide to join, a computer will randomly choose your baby to receive either omeprazole liquid or a matching dummy medicine (placebo) with no active drug. This is a 50/50 chance, like tossing a coin. Neither you nor your doctor will know which one your baby receives, though doctors can find out immediately in an emergency.

Your baby will take the liquid medicine for four weeks. During this time, the study team will phone you at two weeks to check on your baby's well-being. At four weeks, you will complete a short online questionnaire about their symptoms. The team will stay in touch periodically over the next six months to check on your baby's growth, general health, and family well-being. Questionnaires can be easily completed on a phone or computer, or on paper if preferred.

Potential risks and benefits

Your baby might not get a direct benefit from taking part, but the results will help doctors better treat babies with severe reflux in the future. Omeprazole is already widely used in standard NHS care, so the risks are no higher than routine treatment. However, lowering stomach acid over time might slightly raise the chance of tummy bugs, chest infections, or bone fractures. The study team will monitor your baby closely. Your baby's well-being always comes first, and you can withdraw from the study at any time without it affecting your baby's normal healthcare.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

Not provided at time of registration
City only
-, England

Common questions

What is a placebo?

A placebo is a dummy treatment that looks and tastes like the real medicine but contains no active drug. It helps researchers find out if the actual medicine makes a genuine difference.

Will I know if my baby is receiving omeprazole or the dummy medicine?

No, neither you nor your doctor will know during the study. However, if your baby becomes unwell and needs urgent medical care, the team can check immediately.

Can I leave the study if my baby's reflux gets worse?

Yes. You can leave the study at any point. Your baby's doctor will always prioritise your child's comfort and can switch them to alternative treatments if needed.

How much time will the study take up?

Treatment lasts four weeks, followed by occasional check-ins over six months. Surveys are short and can be completed quickly on your smartphone or computer.

Does taking part cost anything?

No. The study medicine and all related trial support are provided completely free of charge.

How to find out more

- OTTER Trial Team

OTTER@nottingham.ac.uk - Official trial record

Always speak to your GP or specialist before deciding to take part in a study.