How FPIES is diagnosed
There is no blood test or skin test for FPIES. Doctors diagnose it mostly from what happened: what the child ate, when, and what followed. That makes a written record worth bringing to the appointment.
This page will not tell you whether a child has FPIES, or what to do during a reaction. Only a doctor can make the diagnosis.
From what happened, not from a test
The 2017 international guidelines call a careful history the most important tool for diagnosing FPIES. In most children with acute FPIES, the history alone is enough to make the diagnosis.
To build that history, the doctor needs details of every possible reaction: what happened, how long after the food it began, every food that might be involved, and whether it happened again when the same food was given again.
The guidelines also set out the criteria doctors apply.
Why FPIES is often recognized late
An infant can have several reactions before anyone thinks of FPIES. Early episodes are often taken for a stomach virus, or checked as a possible serious infection.
The guidelines put the delay down to three things: symptoms that could have other causes, no test that settles it, and how few doctors know the condition.
- 5 months First episode
- 7 months Diagnosis
In an Australian study of 230 infants with FPIES, the median age was 5 months at the first episode and 7 months at diagnosis. Australia, 2012–2014.
What tests can and cannot show
The usual allergy tests, skin prick tests and IgE blood tests, are negative in most children with FPIES when it is first diagnosed. The guidelines advise against using them routinely to find the foods involved, because FPIES does not work through IgE.
A negative allergy test does not rule FPIES out for that food.
A doctor may still order them to look for the immediate kind of food allergy, which some children with FPIES also have.
Blood tests and other checks can help rule out other illnesses. No blood test, scan or biopsy confirms FPIES.
The oral food challenge
When the history leaves the diagnosis unclear, the guidelines name the oral food challenge as the gold standard. The food is given in measured amounts, and the child is watched for several hours.
It is done under medical supervision, where fluids can be given straight into a vein if a reaction comes. The guidelines advise against challenging at home a food suspected of causing FPIES reactions.
Many children with a clear history do not need one at diagnosis. Challenges are also used later, to see whether FPIES has been outgrown.
A food trial and a food challengeWhat to write down before the appointment
The FPIES Foundation's medical advisers list the questions a specialist needs answered. Families there suggest writing the answers down beforehand and bringing them, because it is hard to remember everything during the appointment.
The FPIES Foundation's full list of questionsEach episode
What happened, how many times it has happened, and whether it was the same each time.
The food
Which foods were involved.
The times
When the food was eaten, and how long after it the first symptom began.
Afterwards
How long it took to recover, and the child's age at the time.
What was done
The care given, at home or in hospital, and any advice you were given for next time.
Test results
Any blood tests done during a reaction. Ask for copies.
A free printable log and chart
Every food on one page, a box for each exposure. Free, no sign-up.
Download the printable (PDF)Tummy Tales keeps the same record
- Works out the time between a meal and a reaction
- Reminds you, in your own words, at the time you choose
- Makes one plain report for the appointment
If your doctor is new to FPIES
FPIES is uncommon, so a doctor may not know it well. The FPIES Foundation suggests raising it before the appointment, by phone, letter or email, with a review article the doctor can read, rather than for the first time in the room.
Specialists who diagnose and follow FPIES are usually allergists or pediatric gastroenterologists.