By Lotta Johansson
If your child often complains of stomach pain, but medical tests and GP visits find nothing wrong, you’re not alone, and you’re not imagining it. Otherwise known as Functional Abdominal Pain (FAP), recurring tummy pain with no clear medical cause affects up to 1 in 5 children, disrupting school attendance, sleep, social activities, and general wellbeing.
What is FAP and how is it different from other gut issues?
Functional Abdominal Pain is characterised by ongoing or recurrent abdominal pain in children, where medical tests fail to reveal an underlying cause.
Unlike conditions such as coeliac disease, lactose intolerance, or inflammatory bowel disease, FAP can’t be detected by a scan or blood test because it isn’t triggered by a visible issue in the gut.
FAP is linked to dysfunction in how the gut and brain communicate rather than a physical problem within the digestive tract. Contributing factors can include gut sensitivity, family history, gastrointestinal movements that are too fast or too slow, anxiety and depression, immune system functioning, and central nervous system processing.
This type of recurring stomach pain is fuelled by complex signalling between the digestive system and the nervous system, which can amplify painful sensations in response to stress, anxiety, or certain foods.
According to the ROME IV criteria—a standardised diagnostic tool used to classify functional gastrointestinal disorders—FAP is considered abdominal pain that is “distinct from any underlying organic pathology.” The disorder is characterised by four main criteria:
- Episodic or continuous abdominal pain that lasts for at least four days a month for at least two months.
- Pain that does not occur solely during eating or menstruation.
- Insufficient criteria for other functional gastrointestinal disorders.
- Abdominal pain that cannot be fully explained by another medical condition.
How does FAP affect children?
Children with FAP often experience pain that is very real, even if doctors can’t “see” a reason for it. The pain may flare up in the morning before school or during times of stress, and can range from mild discomfort to intense cramps.
Other symptoms may include:
- Nausea or headaches
- Fatigue or trouble sleeping
- Sensitivity to noise or certain foods
- Anxiety or low mood
- Disruption to daily routines like school, sport, or family time
Because there is no obvious medical explanation, parents may worry about overlooking a serious medical condition, while children may feel misunderstood and anxious about their pain not being taken seriously.
This creates a cycle where pain leads to anxiety, which in turn worsens the pain and perpetuates ongoing symptoms. While FAP doesn’t have a visible underlying cause, it can significantly impact a child’s health—contributing to heightened sensitivity to light, sound, or diet, as well as fatigue, sleep issues, anxiety, depression, headaches, nausea, and joint pain.
Treatment options for FAP
While there’s no quick fix for FAP, taking a holistic approach is the best way to soothe little tummies.
Top tips for parents:
- Stick to a routine, particularly around meals, sleep, and school, to help children and teenagers regulate their bodies and reduce anxiety-driven symptoms.
- Provide healthy meals. While there is no specific FAP diet, some children may benefit from tracking food triggers or reducing high-FODMAP foods under the supervision of a qualified medical professional.
- Psychological support in the form of cognitive behavioural therapy (CBT) and relaxation techniques has strong evidence for helping kids cope better with FAP.
- Simply validating your child’s experience can alleviate anxiety and reduce symptoms. Explaining that their pain is real—even if no disease is causing it—can be a powerful form of support.
In contrast to limited success with some medications (with 40% of children remaining symptomatic), growing evidence supports probiotics as a promising treatment option for FAP.
Expert consensus suggests probiotics should be used alongside primary strategies such as diet modifications and increased physical activity. It’s recommended that probiotics be trialled for at least six to eight weeks for best results.
When to see a doctor for FAP
When dealing with FAP, it’s important for your child to see a GP or paediatrician to rule out more serious causes of tummy pain—such as infections, allergies, or gastrointestinal conditions.
If FAP is diagnosed, ask your doctor:
- Should we see a psychologist, dietitian, or paediatric GI specialist?
- What strategies should we try first?
- Are probiotics a good option for my child?
- How can we track symptoms and measure improvement?
FAP has long been ignored as an invisible condition, but parents today have more information and treatment options than ever to get their child back on track. With the right tools, FAP can be managed—helping kids return to being healthy, happy, and pain-free.
Lotta Johansson is a microbiologist and is part of the scientific affairs team at BioGaia.