Most fevers come down effectively with over-the-counter pain relievers, fluids, and rest. A fever is generally considered 100.4°F (38°C) or higher when measured by mouth, and in adults, temperatures below 103°F (39.4°C) are typically not dangerous. The goal isn’t always to eliminate a fever entirely, since it’s part of your body’s immune response, but to make yourself or your child more comfortable while the underlying illness runs its course.
Why Your Body Runs 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 raises your body’s internal thermostat to a new, higher set point. Your body then works to reach that new target through shivering, increased muscle tension, and narrowing blood vessels near the skin (which is why you feel cold even though your temperature is climbing). Fever-reducing medications work by blocking the production of that chemical messenger, allowing the thermostat to reset back to normal.
Over-the-Counter Medications
Two medications are the main tools for bringing down a fever: acetaminophen (Tylenol) and ibuprofen (Advil, Motrin). Both are effective, but they work through different pathways, which is why they can be used together when needed.
Acetaminophen
Adults and teenagers can take 650 to 1,000 mg every four to six hours as needed. The hard ceiling is 4,000 mg in 24 hours, though extra-strength formulations cap the recommendation at 3,000 mg per day. Going over that limit raises the risk of serious liver damage. For children, doses are weight- and age-based: a 2- to 4-year-old typically takes 160 mg per dose, a 6- to 9-year-old takes 320 mg, and an 11- to 12-year-old takes 320 to 480 mg, all on the same every-four-to-six-hours schedule. Children under 2 need a dose determined by their doctor.
Ibuprofen
Ibuprofen is particularly effective for fever and has the added benefit of reducing inflammation. Take it with food or milk to avoid stomach upset. For children 6 months to 2 years, the dose is based on body weight and how high the fever is: roughly 5 mg per kilogram of body weight for fevers under 102.5°F, and 10 mg per kilogram for higher fevers. Ibuprofen has not been established as safe for infants under 6 months. Older adults should use caution because of the potential for kidney problems, and anyone with aspirin sensitivity should avoid it entirely.
Alternating the Two
If a single medication isn’t bringing the fever down enough, alternating acetaminophen and ibuprofen is a well-studied option. A 2024 meta-analysis in the journal Pediatrics found that alternating the two medications was roughly five times more effective than acetaminophen alone at keeping children fever-free at the six-hour mark. Combined or alternating use showed no increase in side effects compared to either drug used alone, as long as doses stayed within recommended limits. If you alternate, a common approach is to give one medication, then give the other three hours later, so you’re not doubling up on the same drug too soon.
Never Give Aspirin to Children
Aspirin is linked to Reye’s syndrome, a rare but potentially fatal condition affecting the brain and liver, in children and teenagers with viral illnesses like the flu or chickenpox. This applies to any product containing aspirin, which sometimes appears on labels as acetylsalicylic acid, salicylate, or salicylic acid. Stick with acetaminophen or ibuprofen for anyone under 18.
Cooling Methods That Help
A lukewarm sponge bath can provide relief, especially for children. Use water between 90°F and 95°F (32°C to 35°C), and sponge for 20 to 30 minutes. Stop immediately if shivering starts, because shivering actually drives body temperature up. If the person doesn’t feel better afterward, there’s no benefit to repeating it.
Do not use cold water, ice baths, or rubbing alcohol. These cool the skin too quickly, which triggers intense shivering and can cause body temperature to rebound even higher. A cool compress on the forehead is fine for comfort but won’t significantly lower core temperature on its own.
Dress in light, breathable clothing and keep the room at a comfortable temperature. Bundling up in heavy blankets traps heat and can push a fever higher.
Staying Hydrated
Fever increases fluid loss through sweating and faster breathing. Children with a persistent fever may need roughly 1 mL of extra fluid per kilogram of body weight for every degree Celsius above normal, every hour, on top of their usual intake. In practical terms, that means offering small, frequent sips of water, diluted juice, broth, or an oral rehydration solution throughout the day.
Watch for signs of dehydration: no tears when crying, dry lips and mouth, and a generally ill appearance. If a child has at least two of those signs, they may already have a meaningful fluid deficit. For adults, dark urine, dizziness when standing, and a dry mouth are the clearest signals that you need to drink more.
How Long a Fever Typically Lasts
Most fevers from viral infections (colds, flu, stomach bugs) peak within the first two to three days and gradually resolve within five days. A fever lasting longer than five days warrants a call to your doctor, as it may point to a bacterial infection or another cause that needs specific treatment. Bacterial infections often produce fevers that don’t improve on their own and may come with more localized symptoms like ear pain, a worsening cough, or painful urination.
Fever Levels That Need Attention
Not every fever requires a phone call, but certain thresholds and symptoms change the picture significantly.
- Infants under 3 months: Any fever of 100.4°F or higher needs immediate medical evaluation, regardless of how the baby appears.
- Babies 3 to 6 months: A rectal temperature above 102°F (38.9°C), or a lower fever paired with unusual irritability, sluggishness, or poor feeding.
- Children: Temperatures above 104°F (40°C), or any fever accompanied by listlessness, confusion, or poor eye contact.
- Adults: Temperatures above 103°F (39.4°C) that don’t respond to medication.
- Any age: Untreated fevers above 105.8°F (41°C) can be dangerous and require emergency care.
Certain symptoms alongside a fever signal something more serious, regardless of the temperature reading. A stiff neck with pain when bending the head forward, mental confusion, altered speech, strange behavior, or a rash that doesn’t fade when pressed are all reasons to seek immediate medical attention. These can indicate meningitis, encephalitis, or sepsis, all of which need rapid treatment.