Fever in a Frail Older Patient | Always a Warning Sign

Tom is the main caregiver for his mom, Beth. He is worried that she’s sick. He calls the doctor:

“Hi Doctor, I’m worried about my mom. She just doesn’t seem herself. She doesn’t want to get out of bed. She looks weak. She recognizes me but she isn’t talking. She’s not eating either.”

Does she have a fever?

“I’m not sure, she feels kinda warm.”

How do you know when a frail older person has become sick? In this and future posts I will talk about the importance of vital signs.

They are called “vital” signs for a reason.

There is a reason I am emphasizing fever. Dr. Michael Wasserman is a friend and colleague. Long ago, he studied patients who went to the emergency department. Most older people who had a fever were seriously ill. Here is his description of the study:


Covid-19 has made us more aware of the importance of checking the temperature. We have not always been as aware as we are today. I have been involved in the care of thousands of old patients. Caregivers have frequently called with concerns that a patient “looks sick.” One of our first questions is always whether the patient has a fever. The most common response was “I’m not sure, he/she feels warm.”

Fever in an older frail patient should always be taken seriously. If you are caregiving for an older patient, be sure to have a thermometer handy. If a person looks ill, use the thermometer to check temperature.

What is considered a “fever” in older adults?

  • a single oral temperature over 100 degrees Fahrenheit (37.8 C)
  • repeated oral temperatures over 99 degrees (37.2 C)
  • an increase in temperature of 2 degrees above the patient’s usual body temperature. For instance, if a senior’s normal temperature is 96.8 (36.0 C), a temperature of 98.8 (37.1 C) is considered a fever.

In younger people, a normal oral temperature (inside the mouth) is 98.6 degrees. But seniors have a lower normal temperature. Normal temperatures between 97.5 and 98.6 are common.

What kind of thermometer should be used?

Forehead thermometers are a fast way to check the temperature. The temperature on the forehead is used to calculate an oral temperature which is displayed on the thermometer.  These measurements are fairly accurate and avoid the need for skin contact.

To take a forehead temperature, be sure the thermometer is not near anything hot or cold. The temperature should not be taken after exercising or eating. Be sure the forehead is clean and free from lotions or makeup.

Use the thermometer periodically to determine a senior’s baseline temperature. Become familiar with the thermometer and use the same one consistently.

Common Causes of Fever in Older Adults

Think: PUS

Pulmonary: bronchitis, pneumonia, flu, Covid-19

Urinary: urinary tract infections (UTI)

Skin: infections of the skin/cellulitis

Common Myths about Fever

Myth: Dehydration causes fever (not true in adults).

Truth: Fever can cause dehydration because of increased need for fluids. However, dehydration does not cause fever.

Myth: Having too many blankets can cause fever.

Truth: Blankets preserve body heat but do not cause fever. A person who has a fever will feel warm under blankets.

What to do when an older person has a fever

  1. Contact a health care provider as soon as possible. A fever of 102 degree F (38.8 C) is a life threatening emergency.
  2. Check the other vital signs. A heart rate greater than 100, respiratory rate greater than 24, blood pressure less than 100 systolic (the upper number) are all worrisome. I will discuss the other vital signs soon.
    1. If blood pressure is much lower than normal, hold off on blood pressure medications.
    2. If the patient is Diabetic, check the blood sugar. If the blood sugar is lower than normal, hold off on medications for diabetes. The blood sugar can also become too high when a diabetic has an infection. Notify the doctor.
  3. Use acetaminophen (Tylenol) for temperature greater than 101. Remove excess blankets and keep the room cool. But avoid overcooling. Do not use cooling baths or cold towels. Do not use rubbing alcohol.
  4. Notice if the patient is coughing, has pain, urinary problems, or skin problems.
  5. Encourage fluids but do not “force” a person to drink. To avoid choking do not feed a patient flat in bed. Encourage sports drinks or soup. Encourage frequent feedings.
  6. Turn the patient side to side. A person who is sick is less likely to move. This increases the risk of injury to the skin and muscle. Keep sheets clean and dry.
  7. Keep a close eye on the person. Older people with fever are weak. The risk of falling increases. Sometimes when patients fall, it turns out that they are sick and have a fever.
  8. Check for worsening confusion. Confusion increases as a person becomes more ill.

Do older adults always have a fever with an infection?

No. 20-30% of seniors will not have a fever despite a serious infection. As people get older and more frail, the body’s response to an infection becomes weaker. That is one reason older people are more likely to become ill. It is also another reason that any fever needs to be taken very seriously.


  • Fever in an older frail patient is a warning sign that the patient is acutely ill.
  • Normal body temperature varies. It is important to know a senior’s baseline temperature. The same thermometer should be used consistently.
  • When an older patient has a fever, pay special attention to the following issues:
    1. Make sure the patient is comfortable.
    2. Keep the person well hydrated.
    3. The patient is weak and at high-risk for falls and skin injury.
    4. Check vital signs. If the patient is Diabetic, check the blood sugar. Medicines may need to be adjusted.


Which of the following is NOT true?

Warmest Aloha,

[email protected]

PS: I say it over and over again: There's no one more important than the caregiver in the daily life of a frail person.


What to do when an older person has a fever (pdf)

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  1. Pingback: Heart Rate in Frail Older Patients | Too slow, too fast, irregular, and just right – Geriatrics with Aloha

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