Most fevers don’t need to be stopped. A fever is your body’s built-in defense against infection, and in the majority of cases, it resolves on its own within a few days. That said, when a fever makes you or your child miserable, there are safe, effective ways to bring the temperature down and stay comfortable while your immune system does its work.
Why Your Body Creates a Fever
When your immune system detects an infection, it releases signaling molecules that trigger the production of a chemical messenger in the brain’s temperature-control center. This messenger essentially resets your internal thermostat to a higher target. Your body then works to reach that new target by ramping up muscle tone, triggering shivering, and narrowing blood vessels near the skin to conserve heat. That’s why you feel cold and shaky at the start of a fever even though your temperature is climbing.
This elevated temperature isn’t random. It creates a less hospitable environment for many viruses and bacteria while speeding up certain immune responses. Most fevers in both adults and children are caused by common viral infections and resolve without any specific treatment beyond comfort care.
What Counts as a Fever
Normal body temperature varies throughout the day and from person to person, but these are the thresholds that define a fever depending on how you take the reading:
- Rectal, ear, or forehead thermometer: 100.4°F (38°C) or higher
- Oral thermometer: 100°F (37.8°C) or higher
- Armpit thermometer: 99°F (37.2°C) or higher
A temperature below these numbers, even if it feels warm to the touch, isn’t technically a fever.
When to Let a Fever Run Its Course
The decision to treat a fever should be based on how you or your child feels, not the number on the thermometer alone. An elevated temperature doesn’t automatically signal a severe illness, and bringing the number down with medication doesn’t make the underlying infection go away faster. If you or your child has a low-grade fever but is otherwise eating, drinking, sleeping reasonably well, and staying alert, there’s no medical reason to intervene.
Treating a fever makes the most sense when it’s causing significant discomfort: body aches, chills, poor sleep, or an inability to keep fluids down. The goal isn’t to eliminate the fever entirely but to take the edge off so you can rest and stay hydrated.
Over-the-Counter Fever Reducers
Two medications are widely used to lower fevers: acetaminophen (Tylenol) and ibuprofen (Advil, Motrin). Both work by blocking the chemical messenger that resets your thermostat, and both are effective at reducing temperature and relieving aches.
For adults, follow the dosing instructions on the package. Acetaminophen is generally taken every four to six hours, and ibuprofen every six to eight hours. Don’t exceed the daily limits listed on the label, and be aware that acetaminophen is an ingredient in many combination cold and flu products, so check labels to avoid doubling up.
For children under 12, liquid acetaminophen (160 mg per 5 mL) is the standard formulation. Dose by your child’s weight rather than age for accuracy, and give it every four hours as needed, with no more than five doses in 24 hours. Ibuprofen is an option for children six months and older. Extra-strength acetaminophen products (500 mg) should not be given to children under 12, and extended-release versions (650 mg) are restricted to those 18 and older.
One critical rule: never give aspirin to children or teenagers. Aspirin has been linked to Reye’s syndrome, a rare but serious condition that causes swelling in the liver and brain, particularly in children recovering from the flu or chickenpox. The only exception is children on long-term aspirin therapy for specific chronic conditions under a doctor’s supervision.
Staying Hydrated
Fever increases your metabolic rate, which means your body burns through fluids faster than normal. Children with a persistent fever may need roughly an additional 1 mL of fluid per kilogram of body weight for every degree Celsius above normal, per hour. For a 20 kg (44-pound) child with a fever of 39°C (about 102°F), that works out to an extra 20 mL (about two-thirds of an ounce) per hour on top of what they’d normally drink.
You don’t need to measure this precisely. The practical takeaway is to offer fluids frequently. Water, diluted juice, broth, and oral rehydration solutions all work. For breastfed infants, nurse more often than usual. Watch for signs of dehydration: dry lips, fewer wet diapers in children, dark urine in adults, or unusual drowsiness.
Clothing and Environment
Your instinct might be to pile on blankets when you have a fever, especially during the chills phase. Resist it. Bundling up traps heat and can push your temperature higher. Dress in lightweight, comfortable clothes or pajamas and use a single light blanket if needed. Keep the room at a comfortable temperature rather than cranking up the heat.
During the chills phase, when your body is actively trying to reach its new set point, adding a blanket temporarily is fine. Once the shivering stops and you start feeling warm, remove the extra layers so heat can escape naturally.
Skip the Cold Baths
Cold water baths and ice packs are a common home remedy, but research shows they’re counterproductive. Your body interprets the sudden cold as a reason to conserve heat even more aggressively, potentially triggering shivering that drives the temperature back up. A study comparing tepid sponge baths to no sponging found that while sponge-bathed children cooled slightly faster in the first hour, there was no meaningful temperature difference after two hours. The sponged children, however, had significantly higher discomfort scores.
If you want to use water, a lukewarm (not cold) washcloth on the forehead or the back of the neck can feel soothing without triggering a shivering response. But it won’t meaningfully lower a fever on its own.
When a Fever Needs Medical Attention
Age matters enormously. Any infant under 3 months with a rectal temperature of 100.4°F or higher needs to be seen by a doctor promptly, even if the baby seems fine otherwise. For babies 3 to 6 months old, a temperature up to 101°F warrants a call if the baby seems unusually irritable, sluggish, or uncomfortable, and anything above that number should be evaluated. For children 6 to 24 months, a fever above 101°F that lasts more than a day without other symptoms deserves a check-in.
For adults, call your doctor if your fever exceeds 104°F (40°C). Regardless of the temperature reading, seek immediate medical help if a fever comes with any of these symptoms:
- Seizure or loss of consciousness
- Confusion or difficulty staying alert
- Stiff neck
- Trouble breathing
- Severe pain anywhere in the body
- Swelling or inflammation in any body part
- Painful urination or foul-smelling urine
Febrile Seizures in Children
Some children between 6 months and 5 years old experience seizures triggered by a rapid rise in body temperature. These febrile seizures are frightening to witness but are usually harmless. A simple febrile seizure lasts less than 15 minutes, involves the whole body (rather than one side), and happens only once in a 24-hour period. Most are over in under two minutes.
If your child has a febrile seizure, lay them on their side on a safe surface, don’t put anything in their mouth, and time the episode. A seizure lasting longer than 15 minutes, affecting only one side of the body, or occurring more than once in the same day is considered complex and requires emergency evaluation. Even after a simple febrile seizure, it’s worth calling your pediatrician to discuss what happened.