My Child Keeps Complaining of Stomach Pain, But Tests Are Normal? Understanding Functional Abdominal Pain in Children

Your child says their stomach hurts. Again. You have already been to the pediatrician. Blood work is normal. Ultrasound is normal. Stool sample is normal. The doctor says everything looks fine, but the next morning your child is doubled over in pain again. You start wondering: is this real, or is it just an excuse to skip school?

I see this exact scenario in my clinic almost every week. A parent brings their child in for an anxiety evaluation, and when I pull up the medical history, there are two or three hospital visits already on file, sometimes including endoscopies and allergy panels. Everything came back negative. The parents are exhausted and confused. The child feels dismissed. And the pain is very much real.

Recurrent abdominal pain is one of the most common reasons children visit both pediatric and child psychiatry clinics. Studies estimate that 10 to 15 percent of school-age children experience recurrent functional abdominal pain^[1][3], and a substantial proportion of these children also have anxiety. This article explains the "everything is normal but it still hurts" phenomenon through the lens of the gut-brain axis.

What is functional abdominal pain in children?

Functional abdominal pain refers to recurrent belly pain lasting more than two months that persists despite thorough medical evaluation revealing no organic cause, such as inflammation, infection, tumors, or structural abnormalities^[2]. The word "functional" does not mean "imaginary" or "all in their head." It means the gut's function is disrupted, even though its structure is intact.

The Rome IV criteria divide pediatric functional abdominal pain into four subtypes:

• Functional dyspepsia: Upper abdominal discomfort, often with nausea, bloating, or early fullness
• Irritable bowel syndrome (IBS): Abdominal pain with changes in bowel habits, including constipation, diarrhea, or both
• Abdominal migraine: Intense episodic abdominal pain with nausea and vomiting, often with a family history of migraine
• Functional abdominal pain, not otherwise specified: Recurrent abdominal pain that does not fit the other three categories

In my clinical experience, the children who get referred to child psychiatry most commonly have IBS or the "not otherwise specified" type. Regardless of subtype, anxiety is almost always part of the picture.

The gut-brain axis: why anxiety causes real stomach pain

The gut is sometimes called the "second brain," and this is not just a metaphor. The enteric nervous system contains over 100 million neurons, second only to the brain itself. This neural network communicates bidirectionally with the central nervous system via the vagus nerve, forming what researchers call the gut-brain axis^[2].

When a child is anxious or stressed, the brain's stress-response system (the hypothalamic-pituitary-adrenal axis, or HPA axis) kicks in and releases stress hormones. These hormones directly affect the gut in three ways:

• Altered motility: The gut may speed up (causing diarrhea) or go into spasmodic contractions (causing cramping pain)
• Heightened visceral sensitivity: Normal gut signals like gas or peristalsis get amplified by the brain and interpreted as pain
• Compromised gut barrier: Chronic stress shifts the composition of gut microbiota, which can further increase intestinal permeability

So when an anxious child says their stomach hurts, they are not lying. They are not pretending. Their gut is genuinely receiving pain signals from the brain, and the sensation is real^[2]. The difference is that the source of the pain is not a diseased organ. It is the way the brain processes stress.

This is why no amount of ultrasound or endoscopy will reveal the problem. Nothing is wrong with the hardware. The issue is in the software.

How to recognize it: typical patterns of functional abdominal pain

Clinically, functional abdominal pain looks quite different from pain caused by organic disease. The following table is one I frequently use in my initial consultations to help parents understand the distinction:

Table 1: Functional vs. organic abdominal pain

The most classic pattern goes something like this: every weekday morning, the alarm goes off and the stomach pain begins. On bad days, the child cannot make it out the door. But come Saturday, or the first day of summer break, the pain fades or disappears entirely^[4]. Parents often interpret this as avoidance, but the child's body is faithfully reflecting their stress response to school.

Long-term follow-up studies have uncovered another important finding: children with functional abdominal pain are at significantly higher risk of developing anxiety disorders in adolescence and adulthood^[4]. For some children, belly pain becomes the body's way of saying what they cannot yet put into words: "I feel anxious" or "I am scared."

What causes recurrent abdominal pain in children?

Why do some children develop functional abdominal pain while others do not? Current research points to an interplay of multiple factors^[2][7]:

Table 2: Psychological and physiological contributors to functional abdominal pain

In my practice, the most common combination looks like this: a child with a naturally sensitive gut runs into academic or social stress, and the parent's anxious response to the pain creates a reinforcement loop. Stack these three factors together and the abdominal pain becomes chronic.

The way parents respond deserves special attention^[7]. When a child reports stomach pain and the parent immediately cancels all plans, keeps them home from school, and showers them with attention, the child's brain unconsciously links "belly pain" with "safety." This is not manipulation on the child's part. It is a natural consequence of behavioral learning. Over-focusing on pain or routinely allowing the child to opt out of activities can unintentionally make symptoms harder to resolve.

Treatment: from CBT to family strategies

The good news is that treatment for functional abdominal pain in children generally works well, especially when started early.

Table 3: Treatment options for pediatric functional abdominal pain

Cognitive behavioral therapy: the strongest evidence

CBT is currently the psychological intervention with the most robust evidence base for pediatric functional abdominal pain^[5]. A 2022 meta-analysis published in JAMA Pediatrics confirmed that CBT effectively reduces both the frequency and severity of abdominal pain in children, outperforming education alone or watchful waiting.

Here is how CBT addresses the problem on three levels:

• Cognitive: Helping the child identify catastrophic thoughts like "my stomach hurts so I must be seriously ill," and replacing them with more balanced interpretations of bodily signals
• Behavioral: Gradual, structured exposure to pain-triggering situations (such as returning to school), breaking the cycle of avoidance
• Physiological: Teaching diaphragmatic breathing and progressive muscle relaxation to dial down autonomic nervous system overactivation

A full course of CBT typically runs 8 to 12 weekly sessions. Research consistently shows that outcomes improve when parents participate alongside the child, learning how to respond to pain behaviors in ways that support recovery rather than reinforcing symptoms.

Medication: when does it come into play?

Medication plays a relatively limited role in treating functional abdominal pain in children. A 2021 Cochrane systematic review examined the evidence for low-dose tricyclic antidepressants and SSRIs and concluded that "some individual cases may benefit, but the overall quality of evidence is low"^[6].

In my own practice, I consider medication only when:

• Anxiety is so severe that the child cannot attend school at all
• CBT has been tried for 6 to 8 weeks without adequate improvement
• There is a clear co-occurring diagnosis of an anxiety disorder or depression

The purpose of medication in these cases is not to "treat the pain." It is to bring anxiety down to a level where the child can meaningfully engage in therapy.

What parents can do

When it comes to treating functional abdominal pain, parents are just as important as the therapist^[7]. Here are some practical steps:

• Validate the pain: Say "I know your tummy really hurts," not "You are making this up." Dismissing the pain only teaches the child to stop communicating
• Avoid over-focusing: After acknowledging the pain, gently redirect your child's attention to another activity. Repeatedly asking "Does it still hurt?" keeps the spotlight on the symptom
• Maintain normal routines: Unless red-flag symptoms are present, do your best to keep your child in school. Staying home full-time reinforces avoidance
• Resist the urge to doctor-shop: Once organic disease has been ruled out, cycling through more hospitals and more invasive tests deepens the child's belief that something is seriously wrong
• Check your own anxiety: Parental stress is contagious. If you notice you are more worried than your child, consider seeking support for yourself as well

Red flags: when to investigate further

Functional abdominal pain is a diagnosis of exclusion. Before labeling the pain as "functional," organic conditions need to be ruled out, particularly inflammatory bowel disease (IBD), celiac disease, and other conditions that can present as chronic abdominal pain^[9][10].

The following red-flag symptoms are widely recognized in clinical practice. If your child has any of these, seek further medical evaluation promptly:

• Unexplained weight loss: More than 5% of body weight lost in three months
• Blood in the stool or black tarry stools: Indicates possible gastrointestinal bleeding
• Persistent vomiting: Especially bilious (green-tinged) vomit
• Recurrent fevers: Fevers of unknown origin after common infections have been excluded
• Pain that wakes the child from sleep: Functional abdominal pain very rarely disrupts sleep
• Pain consistently localized to the right lower abdomen: Requires evaluation for appendicitis or ileocecal pathology
• Growth faltering: Height or weight deviating significantly from the child's established growth curve
• Family history: A first-degree relative with inflammatory bowel disease

In the absence of red flags, a basic workup consisting of a complete blood count, inflammatory markers, fecal occult blood test^[8], and an abdominal ultrasound is generally sufficient to rule out the major organic causes. There is no need to jump straight to endoscopy or colonoscopy^[10].

Frequently asked questions

Q1: Will my child grow out of functional abdominal pain?

Many children do see improvement over time, but longitudinal research shows that 30 to 40 percent still have gastrointestinal symptoms in adolescence or adulthood, and some develop full anxiety disorders^[4]. Early intervention, especially CBT, can meaningfully shorten the course and reduce the risk of these long-term outcomes. A "wait and see" approach is not recommended.

Q2: What kind of doctor should we see?

Start with a pediatrician or pediatric gastroenterologist to rule out organic disease. If tests are normal, the pain has persisted for more than two months, and there are clear signs of anxiety or stress, the next step is a referral to child psychiatry or a psychologist experienced in pediatric pain. The best outcomes happen when both sides collaborate.

Q3: Is my child faking the pain to get out of school?

Almost certainly not. Gut-brain axis research has clearly established that anxiety directly alters gut motility and visceral sensitivity through the autonomic nervous system, generating real pain signals^[2]. When your child says it hurts, it genuinely hurts. The pain originates in the brain's stress response, not in a structural problem with the gut. Labeling the child as "faking it" only makes them less likely to tell you when something is wrong.

Q4: Is pediatric IBS the same as functional abdominal pain?

IBS is one subtype within the broader umbrella of functional abdominal pain disorders. The umbrella also includes functional dyspepsia, abdominal migraine, and others. What sets IBS apart is that the abdominal pain comes with changes in bowel habits (constipation, diarrhea, or both). Clinically, distinguishing among subtypes helps fine-tune the treatment approach, but the core psychological intervention strategy is the same.

Q5: Should I get allergy testing for my child?

If there is a clear temporal link between a specific food and your child's symptoms (for example, diarrhea every time they drink milk), then testing for lactose intolerance or food allergy makes sense. Without that kind of specific clue, broad allergy panels (IgE, IgG food sensitivity tests) have limited diagnostic value for functional abdominal pain. Evaluating for psychological stressors is usually more productive.

Q6: Do probiotics help with children's abdominal pain?

A handful of small studies suggest that certain strains, such as Lactobacillus rhamnosus GG, may offer modest benefit for functional abdominal pain in children. However, the evidence remains weak, and no major clinical guideline currently recommends probiotics as a primary treatment. There is no harm in trying them, but they should not replace psychological intervention, which remains the most effective approach.

A note from Dr. Tam

In my consulting room, the sentence that brings the most relief to parents is usually this one: "Your child is not tricking you, and there is no mysterious illness hiding from the tests. Their gut is speaking the language of stress."

Treating functional abdominal pain in children was never just about making the belly stop hurting. The deeper goal is helping the child learn to recognize their own emotions, build resilience against stress, and at the same time helping parents understand how to respond to their child's pain in a way that supports recovery.

A few things I want every parent to take away:

• Rule out organic disease first. A basic blood panel, stool test, and ultrasound remain an essential first step
• Do not repeat invasive tests unnecessarily. Once organic disease has been excluded, more endoscopies only deepen the child's fear
• If the pain has lasted more than two months and tests are normal, consider a mental health evaluation. Early intervention typically leads to excellent outcomes
• CBT is the most effective treatment available. It is not just "talking about feelings." It is a structured, evidence-based therapy program
• Parents need support too. Caring for a child with chronic pain is draining. Your own anxiety deserves attention as well

References

1. Vermeijden NK, et al. Epidemiology of Pediatric Functional Abdominal Pain Disorders: A Meta-Analysis. Pediatrics. 2025;155(2):e2024067677. DOI · PubMed
2. Thapar N, et al. Paediatric Functional Abdominal Pain Disorders. Nat Rev Dis Primers. 2020;6(1):89. DOI · PubMed
3. Korterink JJ, et al. Epidemiology of Pediatric Functional Abdominal Pain Disorders: A Meta-Analysis. PLoS One. 2015;10(5):e0126982. DOI · PubMed
4. Shelby GD, et al. Functional Abdominal Pain in Childhood and Long-Term Vulnerability to Anxiety Disorders. Pediatrics. 2013;132(3):475-482. DOI · PubMed
5. Gordon M, et al. Psychosocial Interventions for the Treatment of Functional Abdominal Pain Disorders in Children: A Systematic Review and Meta-analysis. JAMA Pediatr. 2022;176(6):560-568. DOI · PubMed
6. de Bruijn CMA, et al. Antidepressants for Functional Abdominal Pain Disorders in Children and Adolescents. Cochrane Database Syst Rev. 2021;(2):CD008013. DOI · PubMed
7. Hyams JS, et al. Childhood Functional Gastrointestinal Disorders: Child/Adolescent. Gastroenterology. 2016;150(6):1456-1468. DOI · PubMed
8. Zeevenhooven J, et al. Clinical Evaluation of Inflammatory and Blood Parameters in the Workup of Pediatric Chronic Abdominal Pain. J Pediatr. 2020;219:76-82.e3. DOI · PubMed
9. Bouhuys M, et al. Pediatric Inflammatory Bowel Disease. Pediatrics. 2023;151(1):e2022058037. DOI · PubMed
10. Reust CE, Williams A. Recurrent Abdominal Pain in Children. Am Fam Physician. 2018;97(12):785-793. PubMed

Further reading:

• The Complete Guide to Panic Disorder: Symptoms, Causes, and Treatment