How often should you take your temperature if you're sick?

September 28, 2025 •

4 min read

While 98.6°F (37°C) has long been considered the standard, normal body temperature actually varies throughout the day and from person to person. Knowing your typical baseline and understanding when to monitor more closely is crucial for knowing how often should you take your temperature if you're sick? and manage your health effectively.

Quick Summary

The frequency of taking your temperature when sick depends on your symptoms and age, but generally, you should check it when you feel worse, about twice a day, or roughly 30 minutes after taking fever-reducing medication. Monitoring how you feel and noting other symptoms is often more important than the exact temperature reading, especially for older children and adults. For infants, especially those under 3 months with a fever, immediate medical attention is required.

Key Points

Check Your Temperature Twice a Day: For most illnesses, taking your temperature in the morning and evening is enough to establish a consistent pattern.
Watch for Changes in How You Feel: Instead of relying solely on the number, take your temperature if you feel worse, especially if new symptoms appear.
Timing After Medication is Crucial: Take your temperature before medication and wait at least 30-60 minutes after taking a fever reducer to get an accurate reading of its effect.
Use Age-Appropriate Guidelines: Infants under 3 months with a fever need immediate medical attention, while older children and adults can focus more on symptoms and comfort levels.
Don't Over-Monitor: Unless directed by a doctor, checking your temperature constantly can cause unnecessary stress; focusing on your overall well-being is more important.
Seek Medical Advice for High or Persistent Fevers: Contact a healthcare provider for a fever that lasts more than three days, is consistently very high (over 103°F for adults), or is accompanied by other severe symptoms.

General Guidelines for Monitoring Your Temperature

When you're feeling under the weather, knowing when and how often to take your temperature is key to monitoring your illness without becoming overly anxious about the numbers. For most healthy adults, twice a day is a sufficient starting point, but the frequency can change based on how you feel. Instead of obsessing over the number, focus on the overall pattern of your symptoms.

Establish Your Baseline: Before you're sick, it can be helpful to know your normal temperature range. Take your temperature once in the morning and once in the evening for a few days to understand your personal baseline.
The 'Twice a Day' Rule: Once sick, continue taking your temperature at the same times each day. This helps track fluctuations and provides a consistent data point for your doctor, if needed.
Monitor Symptoms, Not Just the Number: Pay attention to how you feel. If you are starting to feel worse, feel particularly warm to the touch, or exhibit new symptoms, it's time for another check.
Don't Overdo It: Unless your doctor specifically advises it, there's no need to check your temperature every hour. Excessive monitoring can cause unnecessary stress and isn't typically more helpful than a consistent, routine check.

Age-Specific Considerations for Temperature Monitoring

When it comes to fevers, age is one of the most critical factors. The guidelines for monitoring a sick infant are very different from those for an adult.

Infants Under 3 Months Old

In babies this young, a fever is considered a medical emergency. If a rectal temperature reads 100.4°F (38°C) or higher, call a doctor immediately.

Always Call a Doctor: Do not simply monitor and wait. A doctor will need to provide further direction.
Monitor Closely: If the infant appears ill but does not have a fever, monitor them very closely for any changes, especially in their feeding and behavior.

Children 3 Months to 4 Years Old

For young children, focus more on behavior than the exact number. If they are acting normally and staying hydrated, a low-grade fever isn't always a concern.

Check Every 4 Hours: If your child has a fever, checking it every four hours is a reasonable interval, especially before administering another dose of fever-reducing medication.
Watch for Red Flags: If the fever rises above 104°F (40°C), or is accompanied by severe symptoms like unusual drowsiness, difficulty breathing, or a new rash, seek immediate medical attention.

Children Over 4 and Adults

For this group, symptoms and comfort level are the primary guides for monitoring and treatment. The fever itself is a sign the body is fighting off infection.

Monitor When Feeling Worse: If you feel an increase in symptoms or overall discomfort, check your temperature. Otherwise, stick to routine checks.
Medical Attention: For adults, a fever lasting more than three days or reaching 103°F or higher warrants a call to your healthcare provider.

Timing Your Temperature Checks with Medication

If you're using fever-reducing medication like acetaminophen or ibuprofen, timing your temperature checks is important for assessing its effectiveness.

Before Medication: Always take your temperature before taking a fever reducer to establish a clear baseline and track its impact.
After Medication: Wait about 30 minutes to an hour after administering medication before checking again. For best results, some experts recommend waiting up to six hours after taking medication to get the most accurate reading. This allows the medication to take full effect and resets your body's temperature.

Comparison of Temperature Monitoring Frequencies


Age Group	Starting Frequency	Key Indicator for Check	When to Seek Medical Help
Infants (<3 mos)	Always check with doctor	100.4°F (38°C) rectal temp	Immediately for any fever
Children (3 mos-4 yrs)	Every 4 hours with fever	Behavior, Fussiness, Lethargy	Fever > 104°F (40°C) or severe symptoms
Adults & Older Children	As needed (typically twice a day)	Feeling worse, new symptoms	Fever > 103°F (39.4°C) or lasts >3 days

How to Take Your Temperature Accurately

Using the right method and technique is vital for an accurate reading. Digital thermometers are widely recommended for their accuracy and safety.

Oral: Wait 30 minutes after eating or drinking. Place the tip under the tongue and close your mouth, waiting for the beep.
Armpit (Axillary): While less accurate, this can be a good screening method. Ensure the armpit is dry and the thermometer is placed in the center, touching skin.
Temporal Artery (Forehead): Often used in doctors' offices, this method is quick and non-invasive. Follow the specific device instructions.
Rectal: Most accurate for infants and young children, though consult your doctor first, especially if the child has certain medical conditions.

Conclusion: Listening to Your Body and Consulting a Professional

Knowing how often should you take your temperature if you're sick? comes down to balancing consistent monitoring with paying attention to your body's other signals. For most common illnesses, regular checks combined with an awareness of your overall symptoms and hydration levels are sufficient. However, for infants and individuals with certain health conditions, or when a fever is unusually high or persistent, it’s always best to consult a healthcare professional. Remember, a fever is often a sign that your body is doing its job, and managing it safely is the priority.

For more information on fever and other illnesses, the Centers for Disease Control and Prevention provides excellent resources on proper fever monitoring for various conditions. https://www.cdc.gov/

Frequently Asked Questions

For infants under 3 months, any fever of 100.4°F (38°C) or higher requires immediate medical attention. For infants over 3 months, you can check every 4 hours or whenever they appear more fussy or uncomfortable.

For adults, call a doctor if a fever lasts more than three days or exceeds 103°F. For infants under 3 months, any fever is a medical concern. For older children, seek medical advice for a fever over 104°F or with concerning symptoms.

Yes, but wait about 30 to 60 minutes after taking medication to assess its effectiveness. Some sources suggest waiting as long as six hours for the most accurate reading.

Yes, forehead thermometers are common and relatively accurate if used correctly by following the device's instructions. Oral thermometers are also accurate for older children and adults who can hold them properly.

Oral temperatures are generally more accurate for most adults and older children. Underarm (axillary) temperatures are less reliable and best used as a screening tool, not for precise readings.

While the number is helpful, how you or your child looks and feels is often a more important indicator of illness severity, especially for older children and adults. Pay attention to symptoms like lethargy, hydration, and difficulty breathing.

A fever is generally defined as a temperature of 100.4°F (38°C) or higher. For adults, a high fever is often considered 103°F or more, while for young children, special attention is needed at any elevated temperature.