Feeling cold while running a fever is completely normal. Your brain has temporarily raised its internal temperature target, so your actual body temperature feels too low by comparison. The result: chills, shivering, and an overwhelming urge to bundle up, even though a thermometer confirms you’re warmer than usual. The good news is that most fevers resolve on their own within a few days, and there are straightforward steps you can take to feel more comfortable while your body fights off whatever triggered the fever.
Why You Feel Cold When Your Temperature Is High
Your brain acts like a thermostat. Normally it keeps your core temperature near 98.6°F (37°C). When your immune system detects an infection, it releases chemical signals called pyrogens that push that set point higher, sometimes to 101°F, 102°F, or beyond. Once the set point rises, your brain perceives your current, normal-range temperature as too cold. It responds the same way it would if you walked outside in January: blood vessels near your skin constrict to trap heat inside, the tiny muscles at the base of your hair follicles contract (goosebumps), and your skeletal muscles start involuntarily contracting. That’s the shivering.
Shivering is your body’s most powerful built-in heater. Those rapid muscle contractions generate a significant amount of warmth, driving your core temperature up toward the new, higher set point. Once your temperature reaches that target, the chills typically ease and you may actually start to feel warm or flushed. Later, when the fever breaks and the set point drops back to normal, you’ll sweat as your body works to shed the excess heat. This cycle of chills followed by sweating can repeat several times over the course of an illness.
What Counts as a Fever
For adults and children over 3, a temperature above about 100.4°F (38°C) is generally considered a fever. A reading above 103°F (39.4°C) is classified as a high fever and warrants closer attention. For children between 3 and 36 months, the threshold for concern drops slightly, and any temperature above 102.2°F (39°C) rectally is considered high. Babies under 3 months old are a special case: a rectal or forehead temperature of 100.4°F (38°C) or higher is a medical emergency that requires an immediate trip to the ER, regardless of other symptoms.
How to Feel More Comfortable
Dress in Layers, Not Heavy Blankets
When chills hit, your instinct is to pile on blankets. A light layer or two is fine, but avoid burying yourself under heavy covers. Trapping too much heat can push your temperature even higher. Use a light blanket while you’re shivering and remove it once the chills pass and you start feeling warm.
Stay Hydrated
Fever increases fluid loss through sweat and faster breathing. Even mild dehydration shows up as decreased urine output, while moderate dehydration causes dry mouth, dark urine, dizziness, and a faster heart rate. Sip water, broth, or an electrolyte drink steadily throughout the day. Small, frequent amounts work better than forcing large volumes at once, especially if nausea is involved. For young children, offer extra fluids after every bout of vomiting or diarrhea.
Consider a Fever Reducer
Over-the-counter pain relievers that contain acetaminophen or ibuprofen can lower your temperature and ease the aching that often accompanies chills. Follow the dosage on the package and be careful not to double up: many cold and flu products already contain acetaminophen, and exceeding 4,000 milligrams of acetaminophen in 24 hours can cause liver damage. Check every label before taking an additional dose. For children, use the weight-based dosing on the pediatric product and avoid giving aspirin to anyone under 18.
Try a Lukewarm Sponge Bath
If your temperature is uncomfortably high, a lukewarm sponge bath can help bring it down gradually. The water should be between 90°F and 95°F (32°C to 35°C), which will feel slightly cool against feverish skin without being cold. Sponge for 20 to 30 minutes, and stop immediately if shivering starts. Never use cold water, ice, or rubbing alcohol. These lower body temperature too rapidly and trigger intense shivering, which actually generates more heat and works against you.
Rest
Shivering burns a surprising amount of energy. Your muscles are essentially exercising on their own, and your metabolism is running faster than normal to fuel the immune response. Sleep and rest let your body direct that energy toward fighting the infection. This isn’t the time to push through a workout or a busy schedule.
What Not to Do
A few common mistakes can make a fever with chills worse. Taking a cold shower or bath causes a sharp spike in shivering that can raise your core temperature further. Drinking alcohol dilates blood vessels and impairs your body’s temperature regulation while also dehydrating you. Bundling a feverish child in heavy clothing or thick blankets can trap heat dangerously. And “sweating out” a fever by exercising or sitting in a hot room offers no benefit and risks overheating.
When a Fever Needs Medical Attention
Most fevers in otherwise healthy adults and older children are uncomfortable but not dangerous. Certain warning signs, however, mean you should seek care promptly. For adults, a temperature of 103°F (39.4°C) or higher combined with any of the following is a reason to go to the emergency room: confusion or difficulty staying alert, trouble breathing, seizures, severe headache, painful or foul-smelling urination, or intense abdominal pain.
For children, the list of red flags includes rapid or labored breathing, difficulty swallowing, inability to keep fluids down, a stiff neck, a new rash, inconsolable crying, or difficulty waking up. A seizure during a fever, while frightening, is relatively common in young children and still warrants immediate evaluation.
For babies under 3 months, any fever at or above 100.4°F (38°C) is an emergency, full stop. Their immune systems are too immature to reliably fight certain infections, and doctors need to evaluate them quickly to rule out serious causes.
How Long Fevers Typically Last
A fever caused by a common viral infection like the flu or a cold usually peaks within the first one to three days and resolves within five to seven days. The chills tend to be worst during the rising phase of the fever, so the first day or two are often the most uncomfortable. If your fever persists beyond three days without improvement, keeps climbing despite fever reducers, or goes away and then returns after a day or more of normal temperatures, those patterns suggest something your body may need help fighting, and it’s worth getting checked out.