What are the symptoms of fever?
The central symptom of a fever is a raised body temperature, measuring above 37.5°C. The recommendation is that this measurement should be taken under the arm in children less than 5 years old. This gives a reasonable guide to the body's 'core' temperature. The actual level of the temperature in fever is not a good guide to how severely ill a child is once they are older than 6 months.
Fever associated with common, self-limiting viral infections such as a cold typically rises and falls over a total of 12-48 hours. Children often complain of feeling cold at the start of a fever. They may look pale and feel shivery, yet will feel hot and dry to the touch. Later they often say they feel hot, and will be sweaty and flushed.
Headache and tummy ache are very common at the same time as fever. Children may be listless, tired and miserable and they may have watery eyes. They may have swollen glands in the neck, under the arms and in the tummy. Drooling may suggest that they have a sore throat, and they feel sick and may be off their food.
What is a febrile convulsion?
Some children have a tendency to febrile convulsions. This is a type of fit triggered by a rapid rise in body temperature. Some children have only one febrile convulsion, ever, but others go on to have them more often. See separate leaflet called Febrile Seizure (Febrile Convulsion).
Febrile convulsions, and fits due to infections such as meningitis, can look very similar. If a child has a fit for the first time, it is important to rule out serious conditions such as meningitis before deciding it is a febrile convulsion.
When does a fever indicate serious illness?
All the symptoms associated with harmless viral fevers can also occur in more serious illness. It can be difficult to determine whether or not your child's fever symptoms should worry you. You know your child better than anyone else. If your child has a fever with symptoms that are unlike those they have had with fevers in the past, consider the possibility of more serious illness.
There are some features of a fever which will help you assess whether you need to seek medical advice:
Features of a fever that help reassure you that your child is not seriously unwell
These include that your child:
- Has normal-coloured skin.
- Responds to you normally.
- Is basically content and will smile.
- Stays awake or awakens quickly and easily when you wake them.
- Has a strong normal cry, or is not crying.
- Has moist lips and tongue.
Features of a fever that suggest your child may be more unwell
- Your child is aged 3-6 months and has a temperature of over 39°C.
- Pale skin, lips or tongue.
- Not responding normally to you.
- Not smiling.
- Wakes only with prolonged effort by you.
- Not wanting to do anything; inactive.
- Dry mouth and lips.
- Poor feeding in babies.
- Reduced wet nappies in babies.
- Attacks of shivering.
Features of a fever that suggest your child is seriously unwell
- Your child is less than 3 months of age and has a temperature of over 38°C.
- Pale/mottled/ashen/blue skin, lips or tongue.
- No response to you.
- Does not wake, or if you wake them, does not stay awake.
- Weak, high-pitched or continuous cry.
- Grunting noises when breathing.
- Indrawing of the muscles between the ribs when breathing (this is particularly true in babies).
- Reduced skin turgor (when you very gently pinch the skin on the back of the hand between your fingers, it does not bounce back but keeps the pinched shape).
- Bulging fontanelle (the 'soft spot' on the top of the head of babies up to about 18 months of age).
- Sunken fontanelle - suggests lack of fluid in the body (dehydration).
Features that suggest your child is dehydrated
Some children who become irritable with a fever do not drink as much as they need, often because they feel sick (nauseated) and things taste strange. In particular, dehydration can develop quickly in a child who is being sick (vomiting) or has diarrhoea. Once dehydration sets in, nausea and vomiting can get worse, which can be a vicious cycle that is hard to break.
Signs of dehydration
- Dry mouth or tongue.
- No tears when crying.
- Sunken appearance to eyes.
- Cool hands and feet.
- Generally becoming more unwell.
- Reduced skin elasticity, or turgor (when you very gently pinch the skin on the back of the hand between your fingers, it does not bounce back but keeps the pinched shape).
- Babies stop passing urine (although this can be difficult to detect if they also have diarrhoea), and the soft spot (on the top of the head) may become sunken in. Small babies can become dehydrated very quickly.
Seek medical advice if you suspect that your child is becoming dehydrated.
Further reading and references
Feverish illness in children - Assessment and initial management in children younger than 5 years; NICE Guideline (Updated August 2017)
Feverish child - risk assessment; NICE CKS, September 2013 (UK access only)
Thompson M, Van den Bruel A, Verbakel J, et al; Systematic review and validation of prediction rules for identifying children Health Technol Assess. 2012 Mar16(15):1-100.
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