How to Take Your Child’s Temperature Safely and Accurately
Types of Thermometers for Children
Parents can use several kinds of thermometers to check a child’s temperature. Glass mercury thermometers are no longer safe because they can break and cause mercury exposure. Instead, most people use a digital thermometer because it is safe, fast, and can check temperature in the mouth, rectum, or under the arm.
Other options include digital ear thermometers, which check heat inside the ear, and temporal artery thermometers that measure temperature on the forehead. Both use infrared technology and give quick results. Digital armpit (axillary) readings are possible but usually less accurate. Some thermometer types are not good choices. Pacifier thermometers do not give reliable results, and fever strips are often inaccurate.
| Thermometer Type | Where Used | Notes |
|---|---|---|
| Digital (Rectal/Oral/Axillary) | Rectum/Mouth/Armpit | Versatile and accurate, but method matters |
| Digital Ear (Tympanic) | Ear canal | Not for babies under 6 months |
| Temporal Artery | Forehead | Gentle and quick, can use while child is asleep |
| Glass Mercury | — | Not recommended, breakage hazard |
| Pacifier & Fever Strips | — | Not reliable, avoid |
Steps for Safe and Proper Use
You should use a thermometer safely for both your child’s comfort and a correct result. Read the instructions that come with your thermometer before use. Clean the tip of the thermometer before and after using it with soap and cool water, unless the instructions say otherwise.
If you use thermometers for both rectal and oral temperatures, keep separate devices and label them clearly. This helps stop the spread of germs. Stay with your child the entire time when taking their temperature. Hold the thermometer so it does not slip or cause discomfort.
Safety Checklist
- Always wash the thermometer before and after use.
- Never leave a child alone when taking a temperature.
- Never use the same thermometer for both rectal and oral readings.
- Read and follow all directions provided with your thermometer.
Choosing a Method Based on Age
The best way to check a temperature depends on your child’s age. Some methods work better for certain age groups and help you get the most accurate results.
Birth to 3 Months: A rectal temperature with a digital thermometer is the most reliable. Sometimes, a temporal artery thermometer also gives a correct reading.
3 Months to 4 Years: Use a rectal thermometer, a digital thermometer under the arm (axillary), or a temporal artery thermometer. For babies under 6 months, do not use ear thermometers. If you are unsure of the results, a rectal reading can confirm.
4 Years and Up: Children this age usually can use an oral thermometer under the tongue for an accurate reading. You can also use armpit, ear, and forehead (temporal artery) methods.
Summary Table
| Age | Recommended Method(s) |
|---|---|
| Birth–3 months | Rectal digital; temporal artery (in some cases) |
| 3m–4 years | Rectal, armpit (axillary), temporal artery |
| 4 years+ | Oral digital, armpit, ear, temporal artery |
How to Take a Temperature
Rectal Temperature (Most Accurate for the Youngest Children)
- Turn on the digital thermometer.
- Put a small amount of petroleum jelly on the tip.
- Lay your child on their back and lift their thighs, or place them belly down on your lap.
- Gently insert the tip ½ to 1 inch into the rectum. Do not force it.
- Wait until the thermometer beeps or signals it is done.
- Remove and read the temperature.
Oral Temperature
- Turn on the thermometer.
- Place the tip under the tongue, toward the back of the mouth.
- Ask the child to keep their lips closed.
- Wait for the thermometer to signal completion.
- Remove and check the result.
- If the child has just eaten or drunk, wait 15 minutes.
Under the Arm (Axillary) Temperature
- Turn on the thermometer.
- Place the tip against the skin in the armpit, not over clothing.
- Hold the child’s arm tight to keep close contact.
- Wait for the beep or signal.
- Read the result.
Ear Temperature (for Children Over 6 Months)
- Turn on the ear thermometer.
- Gently place it in the ear canal, following the device instructions.
- Wait for the reading.
- Remove and check the number.
Temporal Artery Temperature
- Turn on the device.
- Slide it gently across the child’s forehead as directed.
- Wait until it signals the reading is complete.
- Read the temperature.
When you talk with a doctor, share both the number and how you took the temperature, since the method affects how the result is understood.
Recognizing When to Call a Healthcare Provider
Fevers are common and usually show the body is fighting infection. A fever alone does not always mean your child needs medicine or a doctor’s visit. Fever usually means these temperature readings:
- Rectal, Ear, or Forehead: 100.4°F / 38°C or more.
- Oral: 100°F / 37.8°C or more.
- Underarm: 99°F / 37.2°C or more.
Since armpit readings can be less accurate, double-check with a rectal or oral method if you are unsure. Call a health care provider if:
- Your child is younger than 3 months and has a rectal temperature of 100.4°F (38°C) or higher.
- Your child is 3–6 months old, has a temperature up to 102°F (38.9°C), and seems irritable, tired, or uncomfortable, or if the fever is higher than 102°F.
- Between 6–24 months old, the fever is above 102°F for more than a day without other symptoms. If your child has a cough, diarrhea, or other signs of illness, call the doctor sooner if needed.
Medication Guidelines
- For babies under 6 months, use only acetaminophen, and only after seeing a doctor.
- Never give more than the labeled dose.
- Some cold medicines have acetaminophen.
- For ages 6 months or older, you can use ibuprofen if needed.
- Do not give aspirin to children or teens.
Additional Signs to Watch For
- Your child keeps getting sleepier or is hard to wake up.
- Shows signs of dehydration, such as a dry mouth or not urinating.
- Has trouble breathing, keeps vomiting, or has other severe symptoms.
If you are unsure, reach out for medical advice to keep your child safe.
