If your baby or young child is unwell but cannot tell you where it hurts or what feels different, it can be worrying to wonder how a doctor will work out what is wrong. Paediatricians are trained to look beyond spoken symptoms, using changes in behaviour, feeding, sleep, movement and physical signs together with what you have noticed at home.
By combining your observations with a physical examination and, when needed, tests or a period of observation, your paediatrician can build a clearer picture of your child’s health even when your child cannot explain exactly how they feel.
How Can a Paediatrician Diagnose Illness Without a Clear Description?
Paediatric diagnosis is often a process of putting several pieces of information together rather than relying on one symptom. Your paediatrician considers how the illness started, how your child has changed from their usual behaviour, their age and medical history, and what they find during observation and examination.
Your paediatrician may also consider several possible causes before deciding what is most likely. If the diagnosis is still unclear, they may recommend tests or follow-up to understand your child’s condition better.
Why Are Your Observations as a Parent So Important?
You know what is normal for your child, so your observations can help your paediatrician understand what has changed. You can mention changes in feeding, sleep, activity, crying, behaviour or wet nappies.
Try to describe specific changes rather than diagnose the problem yourself. Your paediatrician can then combine what you tell them with their examination and any necessary tests to assess your child.
What Can a Child’s Behaviour Tell the Paediatrician?
Your child’s behaviour can provide valuable information when they cannot explain their symptoms. Changes such as being unusually quiet, irritable, less active or less interested in playing may indicate that they are unwell. If your child is difficult to wake, cannot be woken or becomes markedly less responsive than usual, seek urgent medical help.
Your paediatrician will also notice how your child responds to you, makes eye contact, plays and reacts during the examination. These signs are considered alongside your observations, vital signs and physical examination to understand what may be happening.
How Does Age Change the Meaning of Symptoms?
Your child’s age can change how a symptom is understood. Babies may show illness differently from older children, and their normal heart rate, breathing rate and other signs also vary with age.
Your paediatrician therefore considers your child’s age and development when assessing symptoms. This helps them decide whether your child needs reassurance, closer observation or further tests.
How Do Feeding and Drinking Help Show Whether a Baby Is Unwell?
Your baby’s feeding and drinking habits can give your paediatrician useful clues. Tell them if your baby is feeding less than usual, tiring during feeds, vomiting or having fewer wet nappies.
Reduced feeding or drinking and fewer wet nappies can sometimes suggest dehydration or that your child is becoming more unwell. Your paediatrician will consider these changes alongside signs such as a dry mouth, changes in circulation or breathing, your child’s alertness and the rest of the examination.
How Do Paediatricians Work Out Whether a Young Child Is in Pain?
Your child may show pain through crying, facial expressions, unusual movements, guarding, or refusing to walk. In some settings, your paediatrician may also use an observational pain tool such as FLACC, which considers facial expression, leg movement, activity, crying and consolability when a child cannot reliably describe their pain.
Your observations are helpful too because you know what is normal for your child. The paediatrician then combines these signs with a physical examination to identify the possible cause of the pain.
What Do Vital Signs Tell a Paediatrician?
Your paediatrician can use vital signs such as temperature, heart rate, breathing rate and oxygen saturation to assess your child without relying on speech. These measurements can help identify signs of illness or deterioration.
Because normal readings vary with age, your paediatrician interprets the results alongside your child’s behaviour and examination. This gives them a clearer picture of how unwell your child may be.
What Is a Paediatric Early Warning Score?
When a child is being monitored in hospital, healthcare teams may use a paediatric early warning system to track changes in their condition. NHS England has national PEWS charts for different age groups, which bring observations such as breathing, circulation and other clinical concerns together in a structured way.
A PEWS score does not diagnose a particular illness. Its purpose is to help healthcare teams recognise possible deterioration and decide when a child needs reassessment or escalation of care. Clinical judgement and parental concern remain important alongside the score.
What Does the Paediatrician Look for Before Touching Your Child?
Your paediatrician often starts assessing your child before the physical examination. They may watch their breathing, skin colour, alertness and movement for signs of illness.
They may also notice how your child interacts with you or moves naturally. These early observations give your paediatrician useful clues before they begin touching or examining your child.
| What the paediatrician considers | What it may help show |
| Behaviour and interaction | Whether your child is alert, responsive and acting like themselves |
| Feeding and drinking | Possible illness, dehydration or difficulty coping with feeds |
| Wet nappies or urine output | Hydration and whether intake has reduced |
| Breathing | Effort of breathing, respiratory rate and possible respiratory illness |
| Skin colour and circulation | Possible changes in circulation or oxygenation |
| Temperature | Fever and age-related risk |
| Heart and breathing rate | Whether these readings are within the expected range for your child’s age |
| Physical examination | Possible source of symptoms or signs of serious illness |
| Parent or carer observations | How your child differs from their normal behaviour |
| Tests, where indicated | Additional evidence when the diagnosis remains uncertain |
How Is a Young Child Physically Examined?
Your child may remain close to you during parts of the examination, while a toddler may sometimes be examined while sitting on your lap, playing or holding a familiar toy.
The doctor may check your child’s heart, lungs, tummy, ears, throat, skin and movement. They combine these findings with your observations and your child’s behaviour to understand what may be wrong.
Why Does Developmental Stage Matter During Diagnosis?
Your paediatrician considers what your child normally does at their age and development. Changes such as reduced feeding, less play, unusual quietness or loss of usual skills can provide important clues.
Your child may understand more than they can explain, so the paediatrician may use simple questions, pointing or observation. If your child has communication or developmental differences, their usual behaviour becomes especially important when assessing changes.
How Do Doctors Decide Which Illnesses Are Most Likely?
Your paediatrician looks at the whole picture, including your child’s age, symptoms, medical history, examination and how quickly the illness developed. They consider common causes while also checking for warning signs of more serious conditions.
Sometimes the diagnosis is clear straight away, while other times it remains provisional. Your paediatrician may recommend observation, tests or follow-up to see how your child’s symptoms develop.
When Are Blood, Urine or Other Tests Needed?
Your paediatrician may recommend tests when your child’s symptoms or examination suggest they could provide useful information. Depending on the situation, this may include urine, blood, stool samples, swabs or imaging.
Your child’s age, symptoms and overall condition all influence whether testing is useful. The aim is not to perform every possible test, but to choose investigations that could meaningfully change the diagnosis or treatment while avoiding unnecessary discomfort, radiation or other risks.
Why Might Observation Be Part of the Diagnostic Process?
Your paediatrician may observe your child when the first examination does not give a clear answer. Watching changes in breathing, behaviour, hydration, pain and vital signs can reveal important clues.
Observation is not simply waiting. Your child may be reassessed after rest, fluids or appropriate treatment to see how their overall condition changes and whether new findings appear. However, a child seeming brighter or their temperature falling after fever medicine does not by itself prove that the illness is harmless, so the whole clinical picture still matters.
How Do Paediatricians Recognise When a Child May Be Seriously Ill?
Your paediatrician first checks whether your child may be seriously unwell by looking at breathing, circulation, alertness, hydration and behaviour. Signs such as significantly increased work of breathing, markedly reduced responsiveness, difficulty waking, poor circulation or severe deterioration in feeding and hydration can indicate that a child needs urgent assessment.
Your child may not be able to say they feel very unwell. Your observations, combined with the examination and vital signs, help your paediatrician recognise when further tests or treatment are needed.
When Should You Seek Urgent or Emergency Help?
You should not wait for a routine paediatric appointment if your child appears seriously unwell. For babies and children under 5, call 999 or go to A&E if your child has severe or very fast breathing, blue, grey, pale or blotchy skin, lips or tongue, a rash that does not fade when pressed, is difficult to wake or cannot be woken, or has a seizure. A temperature of 38°C or above in a baby younger than 3 months also needs immediate medical assessment.
Other concerning changes, such as feeding much less than usual, fewer wet nappies, worsening breathing or becoming increasingly less responsive, also need prompt medical advice. If you are unsure how urgently your child needs help, contact NHS 111, and seek emergency help if their condition is rapidly worsening.
Why Can the Diagnosis Change After the First Appointment?
Your child’s symptoms can change, so the diagnosis may become clearer over time. A new symptom or change in your child’s behaviour can give your paediatrician important information.
Some childhood illnesses evolve over hours or days, so findings that were not present at the first assessment may appear later. If your child becomes more unwell, develops a new symptom or is behaving in a way that concerns you, seek further medical advice even if they were assessed recently.
What Information Can You Bring to Help the Paediatrician?
You can help your paediatrician by explaining what has changed and when it started. Tell them about symptoms, temperature, medicines given, feeding, drinking and wet nappies.
You can also bring relevant medical records or videos of symptoms that come and go. Most importantly, explain anything that seems noticeably different from your child’s usual behaviour.
Myth vs Fact
| Myth | Fact |
| A young child must be able to describe their symptoms for a doctor to diagnose them. | No. Paediatricians combine parent or carer observations, behaviour, vital signs, examination and tests where needed. |
| A child who looks brighter after fever medicine cannot be seriously ill. | No. Improvement after fever medicine does not by itself exclude serious illness. |
| Normal tests always prove that nothing is wrong. | No. Test results need to be interpreted alongside the history, examination and how the child’s condition develops. |
| Parents’ observations are less useful than medical measurements. | No. Changes noticed by parents or carers can provide important information because they know what is normal for their child. |
| A paediatric early warning score diagnoses the cause of an illness. | No. PEWS helps healthcare teams recognise possible deterioration; it does not identify the underlying diagnosis. |
Frequently Asked Questions
1. How can a paediatrician diagnose a young child who cannot talk about their symptoms?
A paediatrician uses several sources of information, including your observations, your child’s behaviour, vital signs and physical examination. They may also arrange tests or monitor your child over time if the cause is not immediately clear.
2. Should you bring a video of your child’s symptoms?
A short video can sometimes be useful when a symptom comes and goes, such as an unusual movement, breathing sound or episode that may not occur during the appointment. However, never delay urgent medical assessment in order to record a symptom.
3. What if my child seems fine by the time we reach the appointment?
Tell the paediatrician exactly what you saw earlier and how long it lasted. Information about your child’s behaviour at home can still be useful even if they appear brighter during the consultation, and videos or notes may help with intermittent symptoms.
4. How does a paediatrician know if a baby is seriously unwell?
They assess factors such as breathing, circulation, alertness, hydration, feeding and vital signs. Signs such as difficulty breathing, reduced responsiveness or significant changes in feeding may indicate that urgent assessment or treatment is needed.
5. What if my child’s symptoms are difficult to describe?
You do not need to know the medical name for what you are seeing. Describe exactly what you have noticed, including how your child behaves differently from normal, and let the paediatrician interpret these observations.
6. Does a normal examination always rule out serious illness?
Not always. Many children can be assessed and reassured after a normal examination, but some illnesses develop over time. Your paediatrician may therefore give you advice about warning signs and when your child should be reassessed.
7. Can a paediatrician diagnose illness without doing tests?
Yes. Many childhood illnesses can be assessed using the medical history, your observations, physical examination and vital signs. Tests may only be needed when the diagnosis remains uncertain or there is a reason to investigate further.
8. What is a paediatric early warning score?
In hospital, healthcare teams may use a paediatric early warning system to track changes in observations and help recognise deterioration. It supports clinical assessment but does not tell the team which illness your child has.
9. Can the diagnosis change after the first appointment?
Yes. Your child’s symptoms may develop or change, providing new information that helps clarify the diagnosis. If your child becomes more unwell or develops new symptoms, contact your healthcare professional so they can decide whether another assessment is needed.
10. When should you seek another assessment after seeing a paediatrician?
Seek further advice if your child becomes more unwell, develops new symptoms, is increasingly difficult to wake, has worsening breathing or hydration, or if you remain concerned despite the earlier assessment. Follow any specific safety-netting instructions given by your healthcare professional.
Final Thoughts: Helping Your Paediatrician Understand Your Child’s Symptoms
Diagnosing illness in a young child does not rely on your child being able to describe exactly how they feel. Your observations, your child’s behaviour, feeding, vital signs and physical examination all help your paediatrician build a clearer picture, with tests or follow-up used when further information is needed.
You can support the process by explaining what has changed from your child’s usual behaviour, when symptoms started and how they have developed. If you’re considering seeing a private paediatrician in London, you can get in touch with us at London Paediatric Clinic.
References:
- National Institute for Health and Care Excellence (NICE) (2019) Fever in under 5s: assessment and initial management. NICE guideline NG143. Published 7 November 2019; updated 26 November 2021; last reviewed 30 April 2025. Available at: https://www.nice.org.uk/guidance/ng143
- National Institute for Health and Care Excellence (NICE) (2025) Suspected sepsis in under 16s: recognition, diagnosis and early management. NICE guideline NG254. Published 19 November 2025; last reviewed 5 March 2026. Available at: https://www.nice.org.uk/guidance/ng254
- NHS England (2023) National paediatric early warning system (PEWS) observation and escalation charts. Published 3 November 2023; updated 10 November 2023. Available at: https://www.england.nhs.uk/publication/national-pews-observation-and-escalation-charts/
- Royal College of Paediatrics and Child Health (RCPCH) (no date) Spotting the Sick Child. Available at: https://learning.rcpch.ac.uk/external-resources/spotting-the-sick-child/
- Merkel, S.I., Voepel-Lewis, T., Shayevitz, J.R. and Malviya, S. (1997) ‘The FLACC: a behavioral scale for scoring postoperative pain in young children’, Pediatric Nursing, 23(3), pp. 293–297. Available at: https://pubmed.ncbi.nlm.nih.gov/9220806/
- Van den Bruel, A., Haj-Hassan, T., Thompson, M., Buntinx, F. and Mant, D. (2010) ‘Diagnostic value of clinical features at presentation to identify serious infection in children in developed countries: a systematic review’, The Lancet, 375(9717), pp. 834–845. Available at: https://pubmed.ncbi.nlm.nih.gov/20132979/