Fever and Alzheimer’s Disease

WebMD Medical Reference in Collaboration with the Cecil G. Sheps Center at the University of North Carolina at Chapel HillLogo for UNC Chapel Hill, Cecil G. Sheps Center
Medically Reviewed by Christopher Melinosky, MD on May 04, 2023
4 min read

A fever is usually described as when a person’s body temperature is 100.4 F or higher. Most people get a fever because they’re sick or have an infection. It can be hard to know that someone has one. The best way to tell for sure is to take their temperature by mouth , temporal artery, ear, or rectally with a thermometer.

Contact their doctor right away if they have a single temperature reading that’s higher than 101 F, especially with any of the following:

Call 911 if your loved one has any trouble breathing or is confused or very weak.

Call their doctor if they have:

  • A low-grade fever (under 101 F) for 24 hours or more for no clear reason, even if they seem OK
  • A low-grade fever and have had possible exposure to anyone who may have COVID-19.
  • A low-grade fever and seem sick or their blood pressure is low, breathing rate, or pulse is high
  • A fever and have a weakened immune system because of medications, chemotherapy or radiation treatments, HIV, or other illnesses

When a person with Alzheimer’s disease has a fever, you may notice a change in their behavior. Their energy level may be lower than usual. They might appear flushed or their skin may feel warm or sweaty to the touch, and they may tell you that they’re hot. They also may act sluggish and tired. They may lose interest in what’s going on around them.

Other symptoms may include whole-body weakness or a loss of appetite and thirst. You might see them sweat, shake, shiver, or have chills.

Older people often have a lower body temperature. Knowing your loved one’s normal temperature makes it easier to tell if it’s out of their normal range. Try to take it the same way and in the same place (mouth, underarm, or ear) each time. If their temperature is 2 degrees above what’s normal for them, they likely have a fever.

Most people get a fever because of an illness or infection. You can also get a fever when you get a vaccine shot. In older people, infections of the lungs or airways, urinary tract, or skin are usually the cause.

Respiratory infections can be a minor cold virus or something more serious like Covid-19, flu, or pneumonia. Your loved one might have one if they have a cough, shortness of breath, runny nose, clear their throat often, a hoarse voice, pain when they swallow, or ear pain.

If your loved one has a urinary tract infection, you may notice that they go to the bathroom more often. Their pee might smell foul. They may also seem to be in pain when they pee.

If they have a skin infection, the area may be red or swollen. Their skin may also feel warm to the touch. They may pull away or wince when you touch the infected area.

Have your loved one stay home, rest, and drink plenty of fluids. They can also take acetaminophen (sample brand name: Tylenol) to relieve fever or ibuprofen (sample brand names: Advil, Motrin). These medicines can help bring down a fever. But they are not always necessary. Talk with their doctor to find out what is best.

If your loved one has chills or feels cold, give them a light sheet or jacket. If they cover up with a thick blanket or coat, it might make the fever worse.

If they feel hot, cool them down. You may want to remove any extra layers of clothes or turn on a fan. If they’re near a heat source, such as a space heater or fireplace, get them away from it or turn it off if you can. A lukewarm to cool washcloth on their skin or a lukewarm to cool bath may also help.

Fever can cause dehydration (when your body doesn’t have enough water), so make sure they get plenty to drink.

Watch them closely. Older people can get worse suddenly.

The best way to keep fever from happening is to try to make sure you don’t get sick. Make sure that both you and your loved one see your doctor for routine care. Get all the shots you need, especially for the flu.

Wash your hands thoroughly with soap and water as often as you can, and help your loved one wash theirs. Stay away from other people who are sick. Eat a healthy diet, and get plenty of sleep and exercise.

This is especially important if you’re the main or only person who takes care of your loved one.