A baby’s temperature naturally fluctuates throughout the day—it may rise when they are wrapped in a warm blanket or drop after a bath or on colder days. However, sometimes you might notice your baby feeling warmer than usual or showing signs of illness, such as fussiness, poor feeding, or increased sleepiness. When these signs appear, it’s possible they have a fever.
Baby Temperature Chart: Normal vs. Fever Ranges
Generally, a normal temperature for a baby, when taken rectally, falls between 97°F and 100.3°F. If your baby is having trouble regulating their own temperature, you will typically see larger spikes or drops that don’t resolve naturally, and they will begin to show other symptoms.
This chart outlines the ranges from low to high fever:
| Baby’s Temperature (Rectal) | What Does It Mean? |
|---|---|
| Lower than 95°F | Temperature is too low (Hypothermia) |
| 97° – 100.3°F | Temperature is within the normal range |
| 100.4° – 103.9°F | Your baby has a fever (Low to Moderate) |
| Greater than 104°F | Your baby has a high fever (Serious) |
What is a Low-Grade Fever for a Baby?
Most doctors define a mild or low-grade fever as being between 100.4°F and 102°F. Treatment may not be necessary for a low-grade fever unless your baby’s behavior has changed significantly, they are less than 3 months old, or other concerning symptoms are present. If any of these apply, it is best to consult your doctor immediately.
Watch for Low Body Temperature in Infants
If your baby's temperature is low, the immediate step is to warm them up. Cuddling under a warm blanket or adding an extra layer of clothing are good choices. However, you should call your doctor if their temperature drops below 97°F.
Small babies struggle more to regulate their body temperature. If a baby’s temperature stays low for a long period, it can negatively affect their metabolism and breathing, increasing their overall risk of serious complications. If your baby is cold to the touch or has blue lips or fingers, check their temperature. If it is low, call their doctor.
Common Signs and Symptoms of Fever in Babies
How can you tell if your baby might have a fever? Some of the first indicators are:
- Feeling warm when you touch their forehead or neck with the back of your hand. If their temperature is slightly elevated but they are acting normally, monitor them for other symptoms before worrying.
- Shivering, sweating, or having flushed red cheeks.
- Acting differently, such as seeming weaker or sleepier than usual.
- Being excessively fussy.
- Having a decreased appetite or poor feeding habits.
- Showing a lack of interest in playing or having trouble sleeping.
- Changes in urination, like noticing changes in urine color, odor, or amount when changing their diaper.
- Vomiting.
If your baby shows any of these signs, take their temperature. The best method and the appropriate thermometer depend on your baby’s age.
Common Causes of Fever in Babies
A fever is a symptom, not an illness. It is often a sign that a baby’s immune system is actively fighting off an infection or other issue. Here are some of the most common reasons for fevers:
- A cold or the flu.
- An ear infection.
- A urinary infection.
- Pneumonia.
- Hand, foot, and mouth disease.
- A bacterial infection caused by a severe diaper rash.
- A mild side effect of recent vaccinations.
- Simply being overheated (over-bundled).
When to Talk to a Doctor
Most fevers can be managed at home, but the treatment plan always depends on your baby's age and the severity of the temperature. It is crucial to know when to seek professional medical advice.
Frequently Asked Questions: Baby Fever
A. You should call your doctor immediately if a newborn (under 3 months old) has a rectal temperature of 100.4°F (38°C) or higher. Fever in a young infant is considered a medical emergency.
A. Generally, fever medication is not recommended for mild fevers (below 102°F) unless your baby is uncomfortable or struggling to sleep. Always consult your pediatrician before administering any fever-reducing medication to infants.
A. Teething may cause a slight elevation in temperature, but it is not known to cause a true fever (100.4°F or higher). If your baby has a fever, it is likely due to an underlying illness.