The formula aisle is built to confuse you. Stages 1, 2, 3, hungry baby, comfort, anti-reflux, organic, "closer to breastmilk," premium, value — different boxes, different prices, mostly the same regulated product underneath. For a healthy, term baby, the genuinely meaningful choices are far simpler than the shelf suggests.
Below is what the categories actually mean, where the science supports them, and where the box is doing the work.
Healthbooq gives parents straight, marketing-free guidance on infant feeding, including which formula type to pick and when.
Stage 1: the Default
Stage 1 (also called "first infant milk" or "first milk") is whey-dominant cow's milk formula. The whey-to-casein ratio sits around 60:40, similar to breast milk. It is the appropriate formula for a healthy term baby from birth straight through to 12 months. Both the NHS and the AAP take the same line: there is no nutritional need to change formula at six months.
Every Stage 1 formula sold in the UK is regulated under the same compositional rules (retained EU Regulation 2016/127) and must meet the same minimums and maximums for protein, fat, carbohydrate, vitamins, minerals, and now DHA. Tesco own-brand and Aptamil and Kendamil all meet that same floor. The differences are flourishes — slightly different fat blends, added prebiotics, milk source — that have not been shown to matter clinically for healthy term babies.
Practical translation: if money is tight, the cheapest Stage 1 on the shelf is fine. Pick by price and by what's reliably stocked near you.
Stage 2 / Follow-On: Skip It
Stage 2, "follow-on milk," is casein-dominant and labelled for babies from six months. The NHS, NICE, the World Health Organization, and the European Food Safety Authority all say it is not needed. Stage 1 covers the baby through to 12 months without a switch.
The reason it exists is regulatory. Advertising of Stage 1 (first infant formula) is restricted under UK law to protect breastfeeding. Advertising of follow-on is not. Manufacturers created a near-identical product with a different label so they could put it on television. That is not a reason to buy it.
If you are already on a Stage 2 and your baby is happy, no harm done — just know you do not need to move. If you are about to switch because the box says "from 6 months," save your money.
Hungry Baby Formula (Casein-Dominant)
Hungry baby formula flips the protein ratio: casein-dominant rather than whey-dominant. Casein curdles in the stomach and empties more slowly, in theory keeping a baby fuller for longer. The intended use is older babies who seem hungry on Stage 1 but are not yet weaning.
The evidence is weak. There is no good trial data showing it reduces feed frequency, settles babies, or helps weight gain. Frequent feeding in a young baby — every two hours, sometimes every hour at growth spurts — is normal and expected, not a problem to be solved with thicker milk. NHS guidance is not to use hungry baby formula in babies under six months. If your baby seems unsettled, the better route is a feeding review with a health visitor before changing the formula.
Anti-Reflux (AR) Formula
Anti-reflux formulas are pre-thickened with carob bean gum or rice starch, so the milk is more viscous in the stomach and less likely to come back up. They reduce the volume of visible posseting, which is mostly a laundry issue, not a clinical one.
A few important caveats. Anti-reflux is not a treatment for gastro-oesophageal reflux disease (GORD) — that is a clinical diagnosis with separate management. It should not be made up using a teat with a bigger hole and stirred (the carob gum needs the right water temperature). It is sometimes a useful trial under health visitor or GP guidance for a baby who is regurgitating heavily and unsettled, but it should not be the first move for a baby who is just a bit posset-y but otherwise thriving.
Hydrolysed and Amino Acid Formulas: the Specialist Lane
These are the formulas that actually require a clinical decision.
Extensively hydrolysed formula (eHF) — Nutramigen, Althera, Aptamil Pepti — has cow's milk proteins broken into small peptides that most allergic infants tolerate. First-line for confirmed or strongly suspected cow's milk protein allergy (CMPA), available on NHS prescription.
Amino acid formula (AAF) — Neocate, Nutramigen PurAmino, Alfamino — has no whole protein, only individual amino acids. Used when eHF is not tolerated (about 10% of CMPA babies), in severe CMPA, or in multiple food allergy. Also on prescription.
Partially hydrolysed formula (pHF), sometimes sold as "comfort" formula, is not for CMPA. The protein fragments are still large enough to trigger reactions in allergic babies. It has been studied for allergy prevention with mixed results, and is not currently recommended for that purpose.
Soy formula — not the first move for CMPA. The phytoestrogen content makes UK guidance recommend against soy formula under six months unless there is no alternative. Around 10–15% of CMPA babies also react to soy. There are specific situations (galactosaemia, certain ethical or religious reasons in older infants) where it makes sense, but not as a casual swap.
Lactose-free formula addresses lactose intolerance, which is rare in babies. Most babies a parent worries about have post-viral transient lactose intolerance after gastroenteritis (resolves in a few weeks) or are simply unsettled and not lactose-intolerant at all. Talk to a clinician before switching.
When a Switch Actually Makes Sense
The most common reason parents switch formula is that the baby seems gassy, fussy, or hungry — and most of the time, those are normal newborn behaviours, not formula problems. Switching repeatedly tends to confuse the picture without fixing anything.
Reasons to discuss a switch with your health visitor or GP:
- Symptoms suggesting CMPA: persistent vomiting, blood or mucus in stools, severe eczema, faltering growth, or hives after feeds
- Heavy regurgitation with discomfort, where AR formula trial is being considered
- Confirmed lactose intolerance after gastroenteritis
- Faltering growth that needs a feeding review
Reasons that are usually not the formula:
- Frequent feeding in a young baby
- Some gas and posseting
- Crying in the evenings
- "She seems hungry"
Key Takeaways
Every infant formula sold in the UK has to meet the same legal nutrition floor. Stage 1 (whey-dominant first formula) is fine for healthy term babies from birth all the way to 12 months — there is no nutritional reason to switch to Stage 2 follow-on at six months. Own-brand and premium-brand Stage 1 are nutritionally equivalent. Hungry-baby (casein-dominant), anti-reflux, hydrolysed, amino-acid, and soy formulas exist for specific reasons — only hydrolysed and amino-acid have strong evidence behind them, and those are for cow's milk protein allergy, on prescription, with a clinician deciding.
