Enfamil Reguline vs Enfamil ProSobee (2026): Which Formula Is Better?
A cow's milk constipation formula versus a soy-based dairy-free formula — one targets hard stools while the other eliminates cow's milk entirely. For constipated babies who may also be dairy-sensitive, this is one of the trickiest formula decisions, and it almost always requires a pediatrician's input.
📚 What Each Formula Does
Enfamil Reguline (~$30/12.4 oz) is a cow's milk-based specialty formula designed to relieve constipation through a dual-prebiotic blend and partially hydrolyzed protein. Enfamil ProSobee (~$25/20.9 oz) is a soy protein isolate formula that eliminates cow's milk protein entirely, intended for babies with lactose intolerance, galactosemia, or dairy sensitivity. These formulas address different root causes, and the choice between them depends on whether your baby's issue is constipation, dairy intolerance, or both.
- Reguline targets constipation specifically: its polydextrose + GOS prebiotic blend draws water into the intestines and feeds beneficial bacteria that soften stools
- ProSobee targets dairy avoidance: it replaces all cow's milk protein with soy protein isolate, making it suitable for babies who react to cow's milk
- Reguline contains cow's milk protein (partially hydrolyzed) — it is NOT dairy-free
- ProSobee has no constipation-specific ingredients — in fact, soy protein can actually cause firmer stools in many babies
- ProSobee is lactose-free, using corn syrup solids as its carbohydrate source. Reguline contains some lactose
🔑 Ingredient and Nutrition Comparison
The protein source is the fundamental divider. Everything else — fat blends, vitamins, minerals, DHA/ARA — is largely comparable between the two, meeting AAP standards for infant nutrition.
- Protein: Reguline — partially hydrolyzed nonfat milk + whey protein concentrate (cow's milk-derived). ProSobee — soy protein isolate (plant-based, completely dairy-free)
- Carbohydrates: Reguline — corn syrup solids + lactose. ProSobee — corn syrup solids only (lactose-free)
- Fat: Both use palm olein, soy, coconut, and high oleic sunflower oils
- Prebiotics: Reguline contains polydextrose + GOS at levels shown to soften stools. ProSobee does not contain significant prebiotic fiber
- Iron: Both are iron-fortified. Soy formulas historically had concerns about lower iron bioavailability, but ProSobee's iron levels are adjusted to compensate
- Phytoestrogens: ProSobee contains isoflavones (plant estrogens) naturally present in soy. The AAP considers soy formula safe for full-term infants, though long-term phytoestrogen research is ongoing
💰 Price and Availability
ProSobee is one of the more affordable specialty formulas, while Reguline sits in the mid-range. Both are widely available at major retailers.
- Enfamil Reguline: ~$30 / 12.4 oz (~$2.42/oz of powder)
- Enfamil ProSobee: ~$25 / 20.9 oz (~$1.20/oz of powder)
- ProSobee is significantly cheaper per ounce — roughly half the per-ounce cost of Reguline
- Monthly cost estimate (25 oz/day prepared): Reguline ~$195–210/month vs ProSobee ~$110–130/month
- Both available at Walmart, Target, Amazon, and most pharmacies. ProSobee tends to be more consistently in stock
✨ The Tricky Overlap: Constipated AND Dairy-Sensitive
The hardest scenario is a baby who appears to be both constipated and reactive to cow's milk protein. Neither Reguline (contains dairy) nor ProSobee (can worsen constipation) is a clean solution for this combination. Here's how to approach it.
- Step 1: Determine which symptom is primary. Is the baby constipated with no signs of dairy reaction (no rash, no blood in stool, no excessive vomiting)? → Try Reguline first
- Step 2: If there are clear signs of dairy sensitivity (eczema, blood/mucus in stool, feeding refusal) along with constipation → Skip both and ask your pediatrician about Nutramigen or another hypoallergenic formula
- Step 3: If you try ProSobee for dairy avoidance and constipation worsens, that confirms soy isn't the answer — a hypoallergenic like Nutramigen with added probiotic support may be needed
- The AAP notes that 10–14% of babies with cow's milk protein allergy also react to soy, so ProSobee isn't guaranteed to resolve dairy-related symptoms either
- This scenario is exactly when a pediatrician visit is essential rather than optional — don't spend weeks cycling through formulas on your own
🤝 When to Choose Each Formula
Clear-cut cases make this decision straightforward. The complicated cases belong in your pediatrician's office.
- Choose Reguline if: Baby's only issue is hard, infrequent stools; baby tolerates cow's milk protein with no rash, blood in stool, or vomiting; you want a targeted constipation solution
- Choose ProSobee if: Baby has confirmed lactose intolerance or galactosemia; baby reacts to cow's milk protein with mild fussiness/gas (not severe allergy); family preference for plant-based formula; baby has soft or normal stools but dairy-related discomfort
- Choose neither (see doctor) if: Baby is constipated AND shows dairy allergy signs; baby has blood in stool; baby is losing weight or failing to gain; baby has tried both formulas without improvement
🔮 Bottom Line
Enfamil Reguline and ProSobee target opposite problems. Reguline is the constipation specialist — its dual prebiotics and partially hydrolyzed cow's milk protein directly soften stools. ProSobee is the dairy-free option — its soy protein isolate eliminates cow's milk entirely for babies who can't tolerate it. Don't choose ProSobee to fix constipation (soy often makes it worse), and don't choose Reguline if your baby reacts to dairy (it still contains cow's milk protein). For the unfortunate overlap of both problems, talk to your pediatrician about hypoallergenic alternatives.
- Constipation only, dairy is fine → Reguline (~$30)
- Dairy sensitivity, stools are fine → ProSobee (~$25)
- Both problems → Neither is ideal; consult your pediatrician about hypoallergenic options
- ProSobee is significantly cheaper, but price should not drive this decision — the formula must match the problem