How much will ibuprofen lower a fever

For fevers of 100 to 102° F (37.8 to 38.9° C), cold fluids and little clothing may be all your child needs. Your child may not need acetaminophen.

Call your child's doctor right away if:

  • Your child is less than 3 months old.
  • Your child's fever is over 104° F (40° C).
  • Your child has a seizure.
  • Your child looks or acts very sick.

Call your child's doctor within 24 hours if:

  • Your child is 3 to 6 months old (unless the fever is due to an immunization shot).
  • Your child has had a fever more than 24 hours and you don't know what is causing it AND your child is less than 2 years old.
  • Your child has had a fever for more than 3 days.
  • The fever went away for over 24 hours and then came back.
  • You have other concerns or questions.

Fever - Teen Version

What is a fever?

A fever means the body temperature is above normal. You have a fever if your oral temperature is over 99.5°F (37.5°C).

The body's average temperature when it is measured orally is 97.6°F (36.5°C), but it normally changes during the day. Oral temperature normally can change from a low of 95.8°F (35.5°C) in the morning to a high of 99.4°F (37.5°C) in the late afternoon. Mildly increased temperature (100.4° to 101.3°F, or 38° to 38.5°C) can be caused by exercise, heavy clothing, a hot bath, or hot weather. Warm food or drink can also raise the oral temperature. If you suspect such an effect on your temperature, take it again in a half hour.

How do I take my temperature?

  1. Do not have a cold or hot drink for 30 minutes before you take your temperature.
  2. Turn on the thermometer if you're using the digital type.
  3. Place the tip of the thermometer under one side of your tongue and toward the back.
  4. Wait until the thermometer signals that you can take it out.
  5. Read the display on a digital thermometer.

What causes a fever?

Fever is a symptom, not a disease. It is the body's normal response to infections. Fever helps fight infections by turning on the body's immune system. Most fevers (100° to 104°F, or 37.8° to 40°C) are not harmful. Most are caused by viral illnesses such as colds or flu. Some are caused by bacterial illnesses such as strep throat or bladder infections.

How long will it last?

Most fevers with viral illnesses last for 2 to 3 days. In general, the height of the fever doesn't relate to the seriousness of the illness. How sick you feel is what counts. Fever does not cause permanent harm until it reaches 108°F (42°C). Fortunately, the brain's thermostat keeps untreated fevers below this level.

How can I take care of myself?

  • Extra fluids and less clothing

Drink extra fluids. Cold drinks are helpful. Body fluids are lost during fevers because of sweating.

Dress in light clothing because most heat is lost through the skin. During the time you feel cold or are shivering (the chills), wrap yourself in a light blanket.

If the fever is less than 102°F this is the only treatment needed. Fever medicines are not necessary.

Remember that the fever is helping your body fight the infection. Take medicine only if your fever is over 102°F (39°C) and you are also uncomfortable. You should take either acetaminophen or ibuprofen.

Acetaminophen: Take any one of the acetaminophen products: Tylenol, Anacin-3, Panadol, or Tempra. The dosage is 2 tablets (650 mg) every 4 to 6 hours. 2 hours after they are taken, these drugs will reduce the fever 2° to 3°F (1° to 1.5° C). Medicines do not bring the temperature down to normal unless the temperature was not very high before the medicine was taken. You will need to take repeated dosages of the drugs because the fever will go up and down until the illness runs its course.

Ibuprofen: Ibuprofen is available in 200-mg tablets without a prescription as Advil, Motrin, etc. The dosage is 2 tablets (400 mg) of ibuprofen every 6 to 8 hours. When you use ibuprofen, stop taking acetaminophen.

Avoid aspirin: Doctors recommend that anyone under age 21 years) not take aspirin if they have any symptoms of a cold or viral infection, such as a fever, cough, or sore throat. Aspirin taken during a viral infection, such as chickenpox or flu, has been linked to a severe illness called Reye's syndrome.

As flu season progresses, so does the chorus of advice, professional and otherwise, to drink plenty of fluids and take fever-reducing medications, like acetaminophen, ibuprofen or aspirin.

These recommendations, well-intentioned and firmly entrenched, offer comfort to those sidelined with fever, flu or vaccine side effects. But you may be surprised to learn the science supporting these recommendations is speculative at best, harmful at worst and comes with caveats.

I am an exercise physiologist who specializes in studying how the body regulates fluids and temperature. And based on a wide body of evidence, I can tell you that increased fluid intake and taking fever reducers, whether aspirin, acetaminophen or ibuprofen, may not always help in your recovery. In fact, in some cases, it could be harmful.

There’s a reason why people say fevers should be lowered when sick or after a vaccine. Both aspirin and acetaminophen, such as Tylenol, reduce fever, headaches and muscle aches. But at the same time, seminal and newer studies, including broad meta-analysis studies, show that these medications may weaken the immune response to infection or have unwanted side effects.

What is a fever?

First, some background: Fevers are a regulated increase in core body temperature as a response to unwanted microbial invaders. The more severe the infection, the higher the fever.

Having a fever is not all bad; it’s how the body has evolved to recuperate from an infection. For many species, fevers are advantageous and beneficial for survival.

But fever comes with a cost. A body temperature that’s too high can be deadly. For every increase of 1.8 degrees Fahrenheit, metabolism goes up 10%; the body begins to burn more calories than normal, temperature continues to rise and the body releases hormones to keep fever under control.

Many studies demonstrate what can happen when fever reducers are thrust into this complex dance. It turns out aspirin or acetaminophen may cause infected people to feel better, but they also spread more virus while suppressing their own immune response to the infection.

In one double-blind, placebo-controlled study, healthy people infected with a cold virus who took aspirin or acetaminophen for a week had a reduced immune response and an increase in viral shedding – meaning producing and expelling virus particles from the nose. Another study showed that taking aspirin effectively reduced fever symptoms but increased shedding.

Although some of those traditional studies took place decades ago, their results still hold up today. A recent study warned that if everyone took fever suppressants, there would be even more flu cases and flu-related deaths. Furthermore, elevated body temperature – or fever – can help fight COVID-19 by reducing the growth of the virus within the lungs. In other words, fevers can help the body fight viruses while reducing the rate of death and disease.

Drinking fluids

To prevent dehydration, the Centers for Disease Control and Prevention recommends drinking more fluids when one has a fever or infection, or has received a COVID-19 vaccine. But there is scant scientific evidence to support this recommendation.

How much will ibuprofen lower a fever

Drinking fluids to excess can lead to overhydration. Dina Morozova/iStock via Getty Images Plus

It’s true that drinking fluids when dehydrated is necessary to reduce fever. But not everyone with a fever is dehydrated. For those who aren’t thirsty, forcing fluids beyond thirst, which is often unpleasant, may not be advisable.

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A study that evaluated the advice to “drink plenty of fluids” determined that increasing fluid intake when sick may not offer benefits, and that more high-quality studies are needed. Indeed, there was a potential risk from overhydration. For some people, three liters, or about 12 eight-ounce glasses, is too much. Overhydration can cause nausea and vomiting, headaches and cramps; in severe cases, excessive fluid intake can cause seizures or coma.

Here’s why this happens. To stop dangerous escalations in fever, the body releases antidiuretic hormones. Urination is diminished, so the body retains water through the actions of the kidneys. So if someone with a fever drinks more water than necessary, water intoxication – or hyponatremia, a potentially fatal medical condition in which a patient’s blood sodium levels are too low – could follow.

One study found that nearly a quarter of patients who came to the hospital with COVID-19 had hyponatremia upon admission. In that study, hyponatremia increased the need for breathing support in the form of ventilation. And another study showed that the condition can lead to poorer outcomes in COVID-19 patients.

So maybe it’s time to rethink the conventional wisdom. If the fever is mild or moderate, stay warm, even use blankets, rather than try to actively reduce it. Rest, so your body can fight the fever. Conserve energy because your metabolism is already on overdrive. Use fever-reducing medications sparingly. Drink fluids, but only to tolerance, and preferably when thirsty.

And one final suggestion that should be soothing: When fighting a fever or vaccine side effects, consider sipping warm liquids that contain sodium. Broths containing sodium, like bullion, may help avoid hyponatremia. And although the actual scientific evidence is sparse and conflicting, chicken soup may be a better antidote than water when fending off a fever or flu symptoms.

How much should ibuprofen bring down a fever?

Fever medicine lowers the fever by 2 to 3° F (1 to 1.5° C). You may want to give your child ibuprofen instead. Ibuprofen (Advil) works 2 hours longer than acetaminophen. Give the right dose for your child's weight, every 6 to 8 hours, as needed.

Does ibuprofen work as a fever reducer?

“Ibuprofen is a non-steroid, anti-inflammatory. In other words, it reduces inflammation and pain in the body, and it can also be used as a fever reducer,” Reeder says. Some common brand names of ibuprofen include Advil and Motrin.