A fever is a temperature of 100.4°F (38°C) or higher, and in most cases, the best thing to do is rest, drink plenty of fluids, and let your body do its job. Fever is not an illness itself. It’s your body’s way of fighting off an infection, and most fevers resolve on their own within a few days. That said, there are specific steps you can take to stay comfortable, situations where medication helps, and warning signs that mean you need medical attention right away.
Why Your Body Runs a Fever
When your immune system detects a virus or bacteria, it raises your internal thermostat on purpose. Most infectious organisms thrive at your normal body temperature. Pushing that temperature higher makes it harder for them to survive and reproduce, while simultaneously activating your immune cells to work more aggressively. In other words, a fever is a feature, not a bug. This is why doctors no longer recommend treating every fever automatically. A low-grade fever that isn’t making you miserable may actually be helping you recover faster.
How to Stay Comfortable at Home
The basics matter most: rest and fluids. Your body is burning more energy and losing more water than usual. A healthy adult typically needs around 11.5 to 15.5 cups of total fluid per day under normal circumstances, and you need more when you have a fever. Water is fine, but broth and oral rehydration solutions are especially helpful if you’re also vomiting or have diarrhea, since they replace lost minerals. Watch your urine color as a hydration gauge. Dark yellow means you need to drink more. Headaches, dizziness, dry mouth, and confusion are signs dehydration is getting serious.
Dress in light, breathable clothing and keep your room at a comfortable temperature. Piling on blankets might feel instinctive when you have chills, but heavy layers can trap heat and push your temperature higher. If you want physical cooling, a lukewarm sponge bath (around 90°F to 95°F) for 20 to 30 minutes can help. Never use cold water, ice, or rubbing alcohol. These cool the skin too rapidly, which can cause shivering and actually raise your core temperature. If sponging makes you or your child uncomfortable, skip it. It’s optional.
Eat what you can tolerate. Your appetite will probably drop, and that’s normal. Small, easy meals like soup, toast, or fruit are enough. Sleep as much as your body asks for.
When Fever-Reducing Medication Helps
You don’t need to medicate every fever, but if your temperature is making you miserable, keeping you from sleeping, or climbing above 102°F, over-the-counter fever reducers can bring real relief. Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) both work well. The key safety limit for acetaminophen is no more than 4,000 milligrams in 24 hours, since exceeding that can cause liver damage. Be careful with combination products like cold medicines, which often contain acetaminophen you might not realize you’re doubling up on.
Ibuprofen is generally taken every six to eight hours. It also reduces inflammation, which can help with body aches that often accompany fever. Don’t give aspirin to children or teenagers, as it’s linked to a rare but serious condition called Reye’s syndrome.
Fever Timelines: How Long Is Normal
Most viral fevers peak within the first two days and resolve within three to five days. The fever may come and go during this period, often spiking in the late afternoon or evening. This pattern is normal and doesn’t mean you’re getting worse. For adults, a fever lasting more than three days without improvement warrants a call to your doctor, even if you don’t have other alarming symptoms. A persistent fever can signal a bacterial infection that needs treatment.
Special Rules for Babies and Young Children
Infants handle fever differently, and the age thresholds are strict. Any fever in a baby younger than 3 months requires an immediate call to your pediatrician, regardless of how the baby looks or acts. At that age, the immune system is too immature to reliably fight infections, and a fever can be the only sign of something serious.
For babies 3 to 6 months old, call if the temperature reaches 100.4°F or if the baby seems unusually fussy, lethargic, or unwell even at a lower temperature. Between 6 and 24 months, a fever above 100.4°F that lasts more than one day needs medical evaluation. For children over 2 years old, contact your doctor if the fever persists beyond 72 hours.
Fever in Older Adults and Immune-Compromised People
People over 65 and those with weakened immune systems often run lower baseline body temperatures. This means a reading that looks “normal” or only slightly elevated could actually represent a significant fever for them. Some people with immune deficiencies report temperatures below 101°F even during active infections that would cause high fevers in healthier individuals. This blunted fever response can mask serious infections and delay treatment. If you or someone you care for falls into this category, take any temperature increase seriously, even a small one, especially when paired with fatigue, confusion, or feeling generally unwell.
Warning Signs That Need Immediate Attention
Most fevers are harmless, but certain symptoms alongside a fever point to conditions that can deteriorate quickly. Seek immediate medical care if a fever comes with any of the following:
- Stiff neck with pain when bending the head forward, especially combined with a severe headache and sensitivity to bright light (signs of meningitis)
- Mental confusion, altered speech, or strange behavior
- Difficulty breathing or chest pain
- Persistent vomiting that prevents you from keeping fluids down
- A new rash, particularly one that doesn’t fade when you press on it
- Seizures or convulsions
- Severe abdominal pain
- Pain during urination, which can indicate a kidney infection
Adults with fevers reaching 103°F (39.4°C) or higher generally look and act visibly sick. At that level, even without the symptoms listed above, it’s reasonable to contact your doctor or seek care, particularly if the fever isn’t responding to medication or has come on suddenly without an obvious cause like a cold or flu.