Formula and Diarrhea

I’d like to supplement my breastfed 3-month-old with formula, but it seems to be giving her diarrhea. Is she allergic? What can I use as a supplement?

Dr. Greene’s Answer:

There are several reasons a child could develop mild diarrhea from a formula based on cow’s milk. There could be an intolerance to one of the proteins or perhaps, rarely, to the lactose. (Breast milk contains lactose so babies are very rarely lactose intolerant. That tends to develop after age 2.)

In general, soy formula results in firmer stools, and most kids who don’t tolerate cow’s milk will tolerate soy, though there are some–perhaps 20 percent–who overlap and will keep the loose stools on soy. Most of those kids do well on a hydrolysate formula, such as Nutramigen. Thankfully, most of these intolerances or allergies will get better with age. Kids who can’t take cow’s milk as an infant will usually be able to as they get older. Lactose intolerance is an exception to this–once it sets in, it often continues.

I’m in favor of formulas that have the amount of DHA and ARA recommended by the World Health Organization. Because you are nursing, your baby is getting DHA and ARA from your breast milk. You can be sure your baby is getting a rich supply if you eat one serving of salmon a week (it doesn’t take much).

Dr. Alan Greene

Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.

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  1. Jen*

    My 10 week old baby has been having frequent bowel movement going 6 times a day. He’s on formula and breast milk his stool is not very different from his normal stool should I be worried. He was born at 36 weeks and is my first baby so am worried.

    • Thy

      Hi Doctor ! my son poop around 5 time per day after breast milk formula..before he’s never like this..but after i change breast milk formula to other brand make him poop as i told you above..i really worry about my son…how should i do?

  2. michael

    my daughtreer has explosive diarreah she seems to be having constant bowel movements that have see through like jelly like substance she is on a milk basedpwder infant formula can yu plz help

  3. Ruusa Matheus

    Good day
    I started using S26 Gold for my 6 weeks daughter for just two days now but she passes poo ones a day but they are very loose (watery) it seems like she has diarrhea. Should I stop feeding her the S26 and change to another brand or what?? I feed her only one bottle a day. Please help.

  4. Zuleyma

    Hello DrGreene,

    My 8month old daughter has had diarrhea, feve, and throwing up what ever she eats. I took her to ER because I just did not see a change during the whole day. She didn’t want to eat anything at all — not even juice or milk. Her fever was 101.9. Her head was hot and so was her tummy. They told me at the hospital that everything seemed fine. She has no infection whats so ever. She’s healthy, but I still don’t understand why she still has diarrhea. The doctor didn’t give me any medication to give her. All he said is keep her hydrated. This has been going on for 3 days. I just don’t know whay to do. I don’t want her to lose any weight. If you can, please help me. She is my first daughter.


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