Abdominal Pain in Infants: 8 Possible Reasons Your Baby’s Tummy Hurts

By: Mashette Syrkin-Nikolau, MD, FAAP & Hannibal Person MD, FAAP

Abdominal pain is common in children, especially during a baby's first year. While your baby can't yet tell you when their tummy hurts, you may notice some signs of discomfort. They may be extra fussy and squirmy, for example, and have a change in their bowel movement, sleeping or eating patterns.

There are many different reasons for abdominal pain. Here are some of the causes that can bother babies. As always, be sure to seek medical advice from your pediatrician if you have concerns about your infant's health.

Colic

Colic affects about one in five infants. It is defined as increased fussiness or crying that lasts for three hours at least three times a week. Colic usually starts a few weeks after babies are born and goes away by the time they're about three months old.

Beyond the crying spells, infants with colic are healthy. They should not have any other symptoms like excessive sleepiness, weight loss, poor feeding, vomiting or dehydration. If you are concerned your baby has colic, have them evaluated by their pediatrician to rule out other causes of fussiness and irritability.

How can I help soothe my baby's colic?

The cause of colic is not clear, and there is no one specific treatment. Probiotics, gripe water or gas drops may be worth a try, but discuss it with your pediatrician first. Other ways to help comfort a colicky baby include swaddling, using of a sound machine (white noise), swaying and rocking and walking with your baby, dimming the lights, and giving them a warm bath or running warm water over their head while swaddled.

Colic can be very frustrating and difficult for caregivers. If you're feeling overwhelmed, take a break. Try setting your baby down in their crib for a few minutes, for example, or ask for help from another adult.

Excess gas

All humans produce gas, even the littlest ones. Gas can be especially uncomfortable for newborns, who are still getting used to the sensations of gas and learning to let it pass. The buildup of gas cause discomfort, but it is not dangerous. Gas pain typically peaks at 6-8 weeks of life and improves drastically by 3 months of life.

How to help babies with gas

There are a variety of ways to help reduce excess gas. Avoid feeding your baby when they're overly hungry; they may swallow more air if they are frantically feeding. If your infant is using a bottle, you can consider switching to an anti-colic bottle to reduce excess swallowed air. Burp your infant before, halfway through and after a feed. Keeping them upright after feeding can help their stomach empty.

Holding infants stomach down and increasing tummy time can help move the gas through the intestines. Bicycle leg kicks and tummy massage may also help. You can talk with your baby's pediatrician about trying gas drops and probiotics, but these are not always helpful.

Milk protein allergy (or other dietary protein intolerance)

Cow's milk protein intolerance (also called milk protein allergy), is an abnormal response of the body's immune system to a protein found in cow's milk. Milk protein allergy is very common in infants. Babies with this condition may also have an intolerance to other proteins in the diet, including soy.

There are no specific tests for milk protein allergy. It is diagnosed based on your baby's symptoms. These may include pain with feeds (back arching, fussiness), vomiting, blood or mucous in the stool and weight loss or poor weight gain.

What should I do if my baby has a milk protein allergy?

Treatment for milk protein allergy often starts with eliminating milk protein (casein and whey) and soy from your baby's diet. If you breastfeed your baby, eliminate dairy and soy from your diet, too, so it is free from these proteins. It can take up to 2-3 weeks for the protein to leave the breast milk after taking it out of your diet.

Some families choose to use special formulas with the proteins pre-digested. Most infants will outgrow cow's milk allergy by age one. Dairy and soy can slowly be reintroduced after 1 year of age with guidance from your pediatrician.

Infant constipation

If your baby has hard, infrequent, and sometimes painful stools, they may be constipated. Along with abdominal pain, symptoms of constipation can include vomiting or bright red blood on the stool or with wiping. Always mention any blood in your baby's stool to their pediatrician.

Constipation can be triggered by illness, dehydration, changes in diet, not enough water (if older than 6 months) and changes in routine. Common times for children to become constipated include transitioning to solid foods, toilet training and starting preschool/school. Some children will also hold back bowel movements after experiencing pain with stool passage. It is important to address constipation early on, as the issue can quickly worsen, particularly through stool withholding.

What can I do to help my baby's constipation?

Make sure your baby is getting enough breastmilk or formula and other healthy beverages after that. (Note that while cow's milk can be a healthy beverage for children over a year old, but too much can cause constipation.) Once your baby is ready for solid foods, provide a good source of dietary fiber. Examples of foods high in fiber include prunes, pineapple, pears, peaches, kiwi, avocado, chia seeds, flax seeds, lentils, chickpeas and other beans. See your pediatrician for constipation that lasts for more than a week or if you see blood in the stool.

Pyloric stenosis

Pyloric stenosis is when the muscle between the stomach and the small intestine (the pylorus) thickens and causes a blockage so that food cannot exit the stomach. Common symptoms of pyloric stenosis include forceful, projectile vomiting soon after being fed and poor weight gain, dehydration, irritability and fewer stools. Your baby may also seem hungry even after eating. Pyloric stenosis is most commonly in seen in male newborns between 2-8 weeks of life, though can occur in female newborns.

How is pyloric stenosis treated and diagnosed?

An ultrasound can be used to diagnose pyloric stenosis. The condition is usually repaired surgically. (See "Hypertrophic Pyloric Stenosis (HPS): Help for Babies with Forceful Vomiting.")

Intussusception

Intussusception is when bowel "telescopes" or slides into itself and gets trapped, creating a painful blockage. Although the condition is rare, it is the most common abdominal emergency in children under age 2. Typically, it occurs between 6-12 months of age. Symptoms include periods of intense abdominal pain in which the child abruptly cries and draws their legs to their chest. They may vomit, have a swollen belly and dark, mucus-filled bloody stools.

How is intussusception treated?

If your baby has these symptoms, call your child's doctor or seek medical care right away. The doctor may order an ultrasound or a type of X-ray called an air contrast or barium enema. This test can confirm the diagnosis while also unblocking the the intestine. If the enema does not unblock the intestine, prompt surgery may be needed.

Gastrointestinal (GI) infections

Many types of infections can cause abdominal pain in infants. They can cause vomiting, diarrhea, fever and even blood in stools. Stomach infections are typically caused by a virus but can also be caused by bacteria. Viral stomach infections pass with time and treatments like antibiotics will not shorten the duration of symptoms. Supportive care, including encouraging hydration and treating fevers and pain with acetaminophen, is recommended.

How are bacterial and viral GI infections treated?

Bacterial infections of the gut are much less common. However, bacterial urinary tract infections and pneumonias can also cause abdominal pain and vomiting. Bacterial infections more often require antibiotics. Bring your child to their pediatrician for any concerning symptoms including fever, bloody bowel movements, urination symptoms, excessive sleepiness or breathing problems.

Reflux and GERD

Reflux is the movement of stomach contents into the esophagus and sometimes the mouth. Reflux symptoms are more pronounced in infants because the muscle between the stomach and esophagus (lower esophageal sphincter) is not fully formed. This muscle contracts to help hold food in the stomach and prevent backwards movement in the esophagus. The muscle becomes stronger throughout infancy and is fully developed by age 2 years old.

Babies with reflux are sometimes called "happy spitters" when reflux is without discomfort and have no other signs of illness, like weight loss. Reflux symptoms peak around 4-6 months and then improve over the next 6 months. They are typically resolved before a year, though sometimes can continue until 18-24 months.

Gastroesophageal reflux disease (GERD) is when the reflux of stomach causes irritation of the stomach and/or esophagus lining. This can result in painful feeds, back arching, pulling off the breast during feeds and wanting to feed excessively.

What can help my baby with reflux or GERD?

Giving smaller more frequently feeds and holding baby upright for 15-20 minutes after each feeding can help reduce reflux. Normal baby reflux will not cause weight gain issues, blood in stool or pain with feeds. If you baby is experiencing these symptoms, take them to a healthcare provider for further assessment.

Some babies with GERD require anti-acid medication to reduce acid and prevent injury. Talk to your pediatrician if your baby has any of these symptoms.