Enfamil AR is a thickened, milk-based infant formula designed to reduce frequent spit-up in babies. The “AR” stands for “added rice,” referring to the rice starch mixed into the formula that makes it thicker than standard formulas. In a clinical trial of 104 infants, it reduced spit-up episodes by about 50% within one week. It provides 20 calories per ounce, the same as most standard infant formulas, and is intended as a sole source of nutrition for babies up to 6 months and a major part of their diet through 12 months.
How It Works
Babies spit up because the muscle at the top of their stomach isn’t fully developed yet, allowing milk to flow back up. Enfamil AR addresses this mechanically: the rice starch thickens in the stomach, making it harder for the formula to travel back up the esophagus. This is the same principle behind the old practice of adding rice cereal to bottles, but with the thickener already built in at a consistent ratio.
One important distinction: thickened formulas reduce visible spit-up rather than the actual number of reflux episodes happening inside the body. Your baby may still have reflux events that don’t result in spit-up reaching the mouth. For most babies, this is fine because the main problems with frequent spit-up are mess, discomfort, and concern about whether they’re keeping enough food down. But if your baby has more serious symptoms like poor weight gain, arching, or persistent crying during feeds, the issue may go beyond what a thickened formula can address.
What the Clinical Evidence Shows
Enfamil AR is the only spit-up formula tested in a published, randomized, controlled trial. That study enrolled 104 infants with symptomatic gastroesophageal reflux and compared the thickened formula against a standard one. By the end of the first week, the Enfamil AR group had significantly fewer feedings with regurgitation, lower total regurgitation volume, and fewer episodes of choking, gagging, or coughing during feeds.
The American Academy of Pediatrics recognizes commercially thickened formulas as a reasonable first-line strategy for managing reflux in otherwise healthy, full-term infants who don’t have a cow’s milk protein intolerance. It’s considered a feeding management approach, not a medication, which is why many pediatricians suggest trying it before considering acid-suppressing drugs.
Nutritional Profile
Beyond the rice starch, the formula is nutritionally similar to standard Enfamil products. It contains DHA, a fatty acid important for brain and eye development that experts recommend for infant nutrition. It’s iron-fortified and milk-based, meaning the primary protein source is cow’s milk protein. At 20 calories per ounce with standard mixing, it delivers the same caloric density your baby would get from regular formula or breast milk.
Because it’s milk-based, Enfamil AR is not appropriate for babies with a confirmed or suspected cow’s milk protein allergy. Symptoms of milk protein allergy can overlap with reflux (fussiness, spit-up, digestive distress), which sometimes leads to a trial-and-error period before parents and pediatricians identify the real issue.
Constipation and Other Side Effects
The most commonly reported side effect is constipation. The rice starch that thickens the formula can firm up stools noticeably, and many parents find their babies strain more during bowel movements or go less frequently. This is a well-known tradeoff with rice-thickened formulas. Some parents describe it as a frustrating cycle: the formula solves the spit-up problem but creates a new source of discomfort.
Not every baby will experience this. Some tolerate the formula without any digestive changes. But if your baby is straining, crying during bowel movements, or producing hard, pellet-like stools, it’s worth discussing with your pediatrician. There are strategies that can help, and in some cases switching to a different reflux management approach may be the better call.
One safety note: the AAP has flagged a possible association between thickened feedings and a serious intestinal condition called necrotizing enterocolitis in preterm infants. This formula is designed for full-term babies. If your baby was born premature, talk to your pediatrician before using any thickened formula.
Mixing and Preparation Tips
Enfamil AR is trickier to mix than standard formula because the rice starch tends to clump. Vigorous shaking can introduce air bubbles that make gas and spit-up worse, so the recommended technique is to gently swirl the bottle rather than shake it until the lumps dissolve. If you’re mixing with cold water, the powder takes longer to incorporate. Warming the water slightly before mixing, or running the prepared bottle under warm water afterward, helps the starch dissolve more completely.
Before feeding, test the temperature by shaking a few drops onto the inside of your wrist. It should feel warm, not hot. Because the formula is thicker than standard products, you may need a faster-flow nipple so your baby doesn’t have to work too hard to eat. A nipple that’s too slow can cause frustration during feeds and lead to excess air swallowing, which worsens both gas and reflux.
Who Enfamil AR Is Best For
This formula fits a specific scenario: an otherwise healthy, full-term baby who spits up frequently but is gaining weight normally and doesn’t have signs of a milk protein allergy. Pediatricians sometimes call these babies “happy spitters,” though the volume of laundry and the worry about nutrition can make parents feel anything but happy about it.
If your baby has reflux paired with blood in the stool, a rash, significant weight loss, or extreme fussiness, a thickened standard formula likely isn’t the right starting point. Those symptoms suggest something beyond simple reflux, and your pediatrician will probably want to explore other possibilities, including protein intolerance, before settling on a formula choice.