Follow-on formula is infant milk designed for babies aged 6 to 12 months, meant to be used alongside solid foods rather than as a sole source of nutrition. It sits between first infant formula (suitable from birth) and the transition to whole cow’s milk at age one. While it’s widely available on store shelves, most health authorities say it’s not a necessary purchase for most families.
How It Differs From First Infant Formula
First infant formula, sometimes called “first milk,” is designed to meet all of a newborn’s nutritional needs from birth. Follow-on formula is adjusted for older babies who are also eating solid foods. The most notable difference is iron content: follow-on formulas typically contain higher levels of iron to reflect the increased demands of the 6 to 12 month age range, when daily iron requirements (roughly 0.9 to 1.3 mg per kilogram of body weight) are higher than at any other point in life. Some follow-on formulas also have slightly different levels of protein and certain vitamins.
Despite these differences, the NHS states clearly that first infant formula is the only formula a baby needs throughout the entire first year. There is no evidence that switching to follow-on formula at 6 months provides any benefit. Babies who are eating a variety of iron-rich solid foods alongside their usual first formula are generally getting what they need without the switch.
Why It Exists if It’s Not Necessary
Follow-on formula occupies an unusual space. It was introduced partly because of marketing regulations around infant formula. The WHO’s International Code of Marketing of Breast-milk Substitutes restricts how first infant formula can be advertised. Follow-on formula, marketed for older babies, has historically faced looser advertising rules in many countries, giving manufacturers more room to promote their brand. In 2016, the WHO clarified that follow-on formulas should be classified as breast-milk substitutes, meaning the same marketing protections should apply to any milk product marketed for children up to age 3.
This regulatory gap helps explain why follow-on formula is so visible in stores and advertising. Many parents assume the progression from “Stage 1” to “Stage 2” formula is a required step, similar to moving up a clothing size. It isn’t. The staged numbering is a product category, not a developmental milestone.
When Parents Might Use It
Some parents choose follow-on formula if their baby has low iron stores or isn’t taking well to iron-rich solid foods. In those cases, the higher iron content can help fill a gap. A health visitor or pediatrician might suggest it for a baby with specific nutritional needs. But for a healthy baby who is progressing normally with solids, staying on first infant formula until 12 months is perfectly fine and is the default recommendation from the NHS and similar health bodies.
There’s also no harm in using follow-on formula if you’ve already bought it or if it’s what’s available. The NHS notes that switching between formulas does no documented good or harm. The key point is that parents shouldn’t feel pressured into buying it.
What Comes After 12 Months
At 12 months, most babies can transition from formula to whole cow’s milk as their main drink, alongside water. Whole milk is recommended over reduced-fat options because its higher fat content supports brain development, which is especially active during the first two years of life. By this age, the majority of a child’s calories should be coming from solid foods, so milk shifts from being the primary nutrition source to a complement.
Some brands sell “growing-up milks” or “toddler formulas” for children over 12 months. Like follow-on formula, these are not considered necessary by most pediatric health organizations. Whole cow’s milk, a balanced diet, and (if still desired) continued breastfeeding cover what a toddler needs.
The Bottom Line on Buying It
Follow-on formula is a legitimate, regulated product formulated for babies 6 to 12 months old. It contains adjusted nutrients, particularly more iron, to reflect the dietary needs of older infants. But it’s optional. First infant formula works just as well through the entire first year, and no major health authority recommends switching to follow-on formula as a routine step. If you’re already using first formula and your baby is eating a range of solid foods, there’s no nutritional reason to change.