It’s one of the most common—and concerning—questions parents ask: “Does my baby have a fever?” A rise in body temperature can be alarming, especially in babies under 12 months. But not every warm forehead signals a medical emergency. So, how can you tell when to monitor your child at home and when to call the doctor?
In this blog, we’ll cover:
- What counts as a fever in babies
- When to call a doctor
- Red flags for serious illness, including sepsis
- Trusted resources and where to seek help
At Bright Futures Health, we provide expert paediatric care and guidance when you need it most. Read on to understand fever in babies and when to take action.
What Is a Fever in Babies?
A fever is defined as a body temperature of 38°C (100.4°F) or higher. It’s a natural response to infection and means your baby’s immune system is doing its job. However, fevers in young babies need to be watched closely.
Normal Temperature Range for Babies
- Typical baby temperature: 36.5°C to 37.5°C (97.7°F to 99.5°F)
- Mild fever: 37.6°C to 37.9°C (99.6°F to 100.3°F)
- Fever: 38°C (100.4°F) or higher
Use a digital thermometer to check your baby’s temperature, although invasive measurements such as rectal readings are the most accurate for infants under 3 months.
Common Causes of Fever in Babies
Most fevers are caused by:
- Viral infections (e.g., colds, flu, COVID-19)
- Teething (can slightly raise temperature but rarely over 38°C)
- Vaccinations (mild fever within 24 hours)
- Bacterial infections (e.g., urinary tract infections, ear infections)
While most causes are mild, it’s important to recognise when a fever could signal something more serious.
When Should I Call a Doctor for My Baby’s Fever?
Here are the key guidelines for when to call your GP or paediatrician:
Always seek medical advice if:
- Your baby is under 3 months and has a temperature of 38°C or higher.
- Your baby is 3 to 6 months old and has a temperature of 39°C or higher.
- The fever lasts more than 5 days.
- Your baby shows signs of dehydration (dry nappies, sunken fontanelle, dry lips).
- Your baby is unusually drowsy, irritable, or not feeding well.
- You notice a rash that doesn’t fade when pressed.
Red Flags: Could It Be Sepsis?
Sepsis is a rare but life-threatening condition caused by the body’s extreme response to infection. Babies are particularly vulnerable, and early recognition is critical.
Red Flag Symptoms of Sepsis in Babies:
- Breathing very fast or struggling to breathe
- Floppy, unresponsive, or difficult to wake
- A seizure or fit
- Mottled, blue, or pale skin
- A rash that does not fade under pressure
- Not feeding at all
- High-pitched or abnormal crying
- Very cold hands and feet
If you suspect sepsis, call 999 or go to your nearest NHS emergency department immediately. Early treatment can save lives.
What Should I Do If My Baby Has a Fever?
- Keep your baby hydrated with frequent breastfeeds, bottle feeds, or sips of water (if over 6 months).
- Dress them in light layers—don’t overwrap.
- Monitor temperature regularly using a digital thermometer.
- Let them rest—but keep an eye out for any changes.
- You may use paracetamol or ibuprofen suitable for your baby’s age, but only if they seem distressed. Always follow dosage guidelines.
When to Use NHS Services
Call NHS 111 if:
- You’re unsure whether to take your baby to the emergency department.
- Your baby’s fever is persistent or unexplained.
- You need medical advice out of hours.
You can call 111 or use the NHS 111 online service for non-emergency medical advice.
Call 999 or go to A&E immediately if:
- Your baby shows red flag symptoms (see above).
- You suspect sepsis or that your baby is severely unwell.
Can Teething Cause a Fever?
Teething may cause a slight rise in temperature, but it usually doesn’t exceed 38°C. If your baby has a high fever while teething, it’s likely due to another cause and should be investigated.
Preventing Fevers: Is It Possible?
While not all fevers can be prevented, you can reduce your baby’s risk by:
- Keeping up to date with routine vaccinations
- Practising good hand hygiene at home
- Avoiding contact with sick individuals
- Maintaining a clean feeding environment
Final Thoughts
Fevers are common in babies and are often part of the body’s natural defence against illness. However, knowing when to worry and when to wait is essential for maintaining your peace of mind and ensuring your baby’s safety.
At Bright Futures Health, we’re here to help you navigate the challenges of parenting. Our experienced paediatricians can provide reassurance, check your child’s health, and help you know when to take action.
📞 Book an appointment today at Bright Futures Health to get trusted advice and personalised care.
