Most fevers are caused by common infections and will resolve on their own within three to four days. Your main jobs are to stay hydrated, rest, and manage discomfort. A fever is your immune system’s natural response to infection, and in most cases it doesn’t need aggressive treatment. That said, certain temperatures and symptoms do warrant a call to your doctor or a trip to the emergency room.
How to Take Your Temperature Accurately
Before you do anything else, get a reliable reading. A standard digital contact thermometer works well for all ages and provides accuracy similar to the gold-standard rectal method. Place it under your tongue, keep your mouth closed, and wait for the beep. Avoid eating or drinking anything for 15 minutes beforehand, as hot or cold liquids will throw off the number.
Ear thermometers are convenient for adults and children over seven months, but earwax, ear infections, or a small ear canal can skew results. For infants under seven months, stick with a rectal or standard digital thermometer. A reading of 100.4°F (38°C) or above counts as a fever.
Stay Hydrated
Fever increases the rate your body loses water through sweat and faster breathing. Dehydration can make you feel significantly worse and slow recovery. Aim to sip fluids steadily throughout the day rather than forcing large amounts at once. Water is the simplest option, but broth, herbal tea, and drinks with electrolytes (like sports drinks) all help replace what you’re losing.
If swallowing is painful or your stomach is upset, try ice chips, popsicles, or very small sips taken frequently. Avoid caffeinated drinks, which can pull more water out of your system. Watch for signs of dehydration: dry mouth, dark urine, dizziness, and intense thirst. If those appear and you can’t keep fluids down, that’s a reason to seek medical help.
When to Use Fever-Reducing Medication
You don’t need to medicate every fever. A mild fever that isn’t making you miserable can be left alone. But if you’re achy, unable to sleep, or feeling awful, over-the-counter options can help bring the temperature down and improve comfort.
For adults and teenagers, acetaminophen can be taken at 650 to 1,000 mg every four to six hours as needed, with a hard ceiling of 4,000 mg in 24 hours. Some extra-strength formulations cap the daily limit at 3,000 mg, so check the label. Going over the maximum raises the risk of serious liver damage. Ibuprofen is another option, typically taken at 200 to 400 mg every four to six hours. Don’t combine the two without guidance from a pharmacist or doctor, and never give aspirin to children or teenagers due to the risk of a rare but serious condition called Reye’s syndrome.
For children, doses of both acetaminophen and ibuprofen are based on weight, not just age. Follow the dosing chart on the package carefully. Ibuprofen should not be given to infants younger than six months.
Cool Down Safely
A lukewarm bath can bring mild relief and help you relax enough to sleep. The key word is lukewarm. Cold baths, cold showers, and ice packs can actually backfire: they trigger shivering, which generates more heat and can push your temperature higher. In children, a sudden cold temperature change can even trigger a febrile seizure.
Skip the old-fashioned alcohol rubdown entirely. Rubbing isopropyl alcohol on the skin creates a cooling sensation as it evaporates, but it does nothing to lower a fever. Worse, alcohol can be absorbed through the skin and become toxic, especially in children. Lightweight clothing and a light blanket are better choices. If you’re shivering, add a layer until the chills pass, then remove it.
Rest and Let Your Body Work
Sleep is one of the most effective things you can do. Your immune system ramps up its activity during rest, and pushing through normal activities when you’re feverish just drains energy your body needs for fighting infection. Cancel what you can. Stay home, stay in bed, and eat when you’re able. Even small amounts of easy-to-digest food (toast, crackers, soup) help maintain your energy.
How Long a Fever Typically Lasts
Most viral fevers run their course in three to four days. You may notice the fever spikes in the evening and drops in the morning, which is a normal pattern. By day three or four, the peaks should be getting lower. If your fever persists beyond three days without improvement, schedule an appointment with your doctor. A lingering fever can signal a bacterial infection or another condition that needs specific treatment.
Temperatures That Need Medical Attention
Call your doctor if your fever reaches 104°F (40°C) or higher. At that level, the risk of complications increases and you may need evaluation even if you otherwise feel stable.
Seek immediate medical care if a fever comes with any of these symptoms:
- Stiff neck, especially pain when bending your head forward
- Confusion, altered speech, or unusual behavior
- Seizure or loss of consciousness
- Difficulty breathing or chest pain
- Severe headache that doesn’t respond to medication
- Rash, particularly one that doesn’t fade when you press on it
- Unusual sensitivity to bright light
- Persistent vomiting
- Severe pain anywhere in the body
- Pain when urinating or foul-smelling urine
These can be signs of meningitis, sepsis, or other serious infections that require urgent treatment.
Fever in Babies and Young Children
The rules change significantly for infants. Any baby under two months old with a temperature of 100.4°F (38°C) or higher should be taken to an emergency department immediately, even if the baby appears to be acting normally. Young infants have immature immune systems, and infections can escalate quickly at this age.
For older children, contact their pediatrician if the fever lasts longer than three days, if the child is listless or making poor eye contact, or if they’re vomiting repeatedly. A child who had a fever after being left in a hot car needs emergency care right away, regardless of temperature. Trust your instincts as a parent: if something feels off about how your child looks or behaves, call your doctor even if the thermometer reading seems modest.