Should you suppress a fever?

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• Misc

The shortest story

Should you let a fever continue or suppress it?

Are there any benefits to letting it continue?

The TL;DR is that:

For the average cold, it doesn‘t much matter one way of the other. Suppressing the fever is unlikely to hurt your recovery. 7 days one way, a week the other.

So you might as well be comfortable.

Caveats:

1. If it gets above 104º . . . get help.
2. This doesn’t address side-effects from medication. The answers here are only about whether the fever itself would have been good for your recovery or not. Do you own research about medication side-effects.

The short story

1. The evidence is changing. For a long time, we regarded fevers with suspicion, and almost dogmatically treated high fevers without thought.
2. But it‘s starting to seem that in severe, life-threatening cases, allowing a fever to sustain can saves patients’ lives, while suppressing can lead to death.

There are some important caveats:

1. The emerging evidence concerns severe, life-threatening scenarios. Not to your average cold. For your average cold, there doesn’t seem to be much of a difference.
2. Fevers beyond 104º may still be dangerous. Getting temperatures down might be an urgently good idea; seek informed help.

The long story

Here’s a NYTimes article:

§ https://www.nytimes.com/2018/05/11/well/live/fever-infection-drugs-tylenol-acetaminophen-ibuprofen-advil-aspirin.html

As it recounts, it’s been a time-withstanding debate whether fevers are casually important in fighting infections, or just a potentially harmful side-effect of fighting them.¹

As the evidence indicates:

Proponents also argue that there is little evidence that fever itself, even a high fever, is harmful.

In 1997, these data led to a large, randomized, placebo-controlled trial of ibuprofen in 455 patients with sepsis, a life-threatening infectious condition. In this study, ibuprofen failed to prevent the worsening of sepsis and failed to decrease the risk of death.

In 2015, the largest study to date was published. Investigators in Australia and New Zealand performed a randomized, placebo-controlled trial of acetaminophen in 700 critically ill patients with fever. They found no difference in the number of days that patients required intensive care, and no difference in their odds of death after 90 days.

So the take-away is:

. . . it is probably safe for you to defer taking anti-fever medicines for minor illnesses. On the other hand, since rigorous clinical trials have shown that these drugs do not worsen outcomes, why not make yourself comfortable?

Why not indeed. ²

§ Ray, Schulman (2015). “ Fever: suppress or let it ride?.” Journal of Thoracic Disease.

Fever will be called pyresis, and counter-measures will be called anti-pyretic, by the way.

While our ability to detect and manage fever has evolved since its conceptualization in the 5th century BC, controversy remains over the best evidence-based practices regarding if and when to treat this physiologic derangement in the critically ill.

What a fun opening sentence.

The two fields of thoughts, just as I outlined, are:

There are two basic fields of thought:

1. fever should be suppressed because its metabolic costs outweigh its potential physiologic benefit in an already stressed host;
2. vs. (II) fever is a protective adaptive response that should be allowed to run its course under most circumstances.

The trend of the evidence is moving in fever of “let it ride.” Slow, and tiny jumps, but noticing the direction:

The latter approach, sometime referred to as the “let it ride” philosophy, has been supported by several recent randomized controlled trials like that of Young et al. [2015], which are challenging earlier observational studies and may be pushing the pendulum away from the Pavlovian treatment response.

The article is filled with wonderful quotes in general:

Complicating this matter is both the heterogeneous etiology of fever as well as practice dogma. While 70% of ICU patients manifest fever, only about 53% are of infectious etiology ( 5). Despite its source, practitioners often seem to possess an ingrained philosophic opposition towards fever, prompting a knee-jerk response to treat that is not supported by high-level evidence in the ICU population.

What would need to be true to support suppressing fevers is:

In general, two critical assumptions form the basis of the argument for treating fevers, neither of which have been experimentally validated:

1. fever is noxious, and
2. suppression of fever will reduce its noxious effect (6,7).

The way the harms of fever are often is:

One condition justifying treatment consideration is when a fever’s metabolic cost exceeds its physiologic benefit, but this again, is challenging to quantify (6,8).

Howevere, there are some terribly scary effects of what happened to iguanas and ICU patients when they were not allowed to maintain a fever:

Patients were randomized to an aggressive treatment group, consisting of acetaminophen 650 mg every 6 hours for fever >38.5 °C with addition of a cooling blanket for temperature of >39.5 °C, or a permissive group where treatment was initiated at a temperature of >40 °C with acetaminophen and cooling blankets. The study had to be terminated at the interim analysis as there were seven deaths in the aggressive group and only one death in the permissive group.

Take, for example, the classic experiment by Kluger et al. in 1981 ( 21, 22). Here, Kluger et al. infected cold-blooded iguanas with bacteria. He gave them the opportunity to seek heat via sunlamps and all but one sought the warmth to raise their temperature. The one who did not was the only one who died. Next, he injected the iguanas with bacteria and gave them antipyretics. The iguanas that were able to mount a fever despite the antipyretic were the only ones that survived. This simplistic experiment, in addition to the biologic plausibility for the beneficial effects of fever, now supported by several key randomized controlled trials, suggests maybe the pendulum is due to swing back to a more permissive approach to fever.

I should note that these were for life-threatening scenarios, not small colds. And there are many other RCTs that did randomise suppressing the fever and could simply find no discernible evidence.

So for colds, it may still be fine to suppress. There is nothing to indicate worse effects. For life-threatening scenarios, there may be evidence accumulating to suggest holding off on suppression.

As for the why permitting fevers might be good for you, the argument is for greater immune competence. This is evolutionary supported:

Is fever good or bad? Scientifically, we just do not know. However, if we take the evolutionary perspective, then blunting of the adaptive febrile response must be maladaptive. Fever is estimated to be more than 4 million years old and has been documented in the phyla Vertebrata, Arthropoda, and Annelida ( 7).

Again, to clarify: we don’t know—but there is a lot of reason to reconsider the dogma.

The pendulum is in swing.

While clinicians will likely continue to argue the validity of the proposed adaptive or maladaptive mechanisms of fever, recent studies such as the one by Young et al. should support reconsideration of the Pavlovian treatment response to elevated temperature in the critical care setting.

What about very high fevers?

There are myths about “high fevers” (as low as 101º or 103º) being dangerous for children or potentially causing brain damage.

These seem largely unfounded, in most cases.

For example, consider the following study:³

Stochetti et al. (2005). “ Impact of pyrexia on neurochemistry and cerebral oxygenation after acute brain injury.” Journal of Neurology, Neurosurgery, & Psychiatry.

It studies the impact of fevers on brain health, especially in the context of neurosurgery where high fevers can be a problem, and it finds that on its own, high temperatures don’t cause damage—that is as long as sufficient oxygenation is being met, and other conditions are fulfilled. If they’re not, fevers do worsen the situation dramatically.

Here’s an article from the Seattle Children‘s Hospital:

(2021). “ Fever - Myths Versus Facts.” Seattle Children’s Hospital.

MYTH. All fevers are bad for children.

FACT. Fevers turn on the body’s immune system. They help the body fight infection. Normal fevers between 100° and 104° F (37.8° - 40° C) are good for sick children.

MYTH. Fevers above 104° F (40° C) are dangerous. They can cause brain damage.

FACT. Fevers with infections don’t cause brain damage. Only temperatures above 108° F (42° C) can cause brain damage. It’s very rare for the body temperature to climb this high. It only happens if the air temperature is very high. An example is a child left in a closed car during hot weather.

MYTH. Anyone can have a seizure triggered by fever.

FACT. Only 4% of children can have a seizure with fever.

MYTH. Seizures with fever are harmful.

FACT. These seizures are scary to watch, but they stop within 5 minutes. They don’t cause any permanent harm. They don’t increase the risk for speech delays, learning problems, or seizures without fever.

MYTH. All fevers need to be treated with fever medicine.

FACT. Fevers only need to be treated if they cause discomfort (makes your child feel bad). Most fevers don’t cause discomfort until they go above 102° or 103° F (39° or 39.5° C).

MYTH. Without treatment, fevers will keep going higher.

FACT. Wrong, because the brain knows when the body is too hot. Most fevers from infection don’t go above 103° or 104° F (39.5°- 40° C). They rarely go to 105° or 106° F (40.6° or 41.1° C). While these are “high” fevers, they also are harmless ones.

MYTH. With treatment, fevers should come down to normal.

FACT. With treatment, most fevers come down 2° or 3° F (1° or 1.5° C).

MYTH. If you can’t “break the fever”, the cause is serious.

FACT. Fevers that don’t come down to normal can be caused by viruses or bacteria. The response to fever medicines tells us nothing about the cause of the infection.

MYTH. Once the fever comes down with medicines, it should stay down.

FACT. It’s normal for fevers with most viral infections to last for 2 or 3 days. When the fever medicine wears off, the fever will come back. It may need to be treated again. The fever will go away and not return once the body overpowers the virus. Most often, this is day 3 or 4.

MYTH. If the fever is high, the cause is serious.

FACT. If the fever is high, the cause may or may not be serious. If your child looks very sick, the cause is more likely to be serious.

MYTH. The exact number of the temperature is very important.

FACT. How your child looks and acts is what’s important. The exact temperature number is not.

MYTH. Oral temperatures between 98.7° and 100° F (37.1° to 37.8° C) are low-grade fevers.

FACT. These temperatures are normal. The body’s normal temperature changes throughout the day. It peaks in the late afternoon and evening. A true low-grade fever is 100° F to 102° F (37.8° - 39° C) .

SUMMARY. Keep in mind that fever is fighting off your child’s infection. Fever is one of the good guys.

Fascinating overall, right? Given they are the Seattle Children’s Hospital website, there is a bit more reason to trust them than a random article on the internet. They specialise in this stuff.

In the best scenario, it’s written by doctors who have both a theoretical understanding of the field and an emprical day-to-day experience working with children every day.

They call fevers between 100–104º “normal.” 104–108º is high, but it won’t cause brain damage, and seizures aren’t necessarily fatal or concerning.

My mother, who is a doctor, told me of her time getting medical training in the USSR. They did things differently there, she said, compared to the U.S. at the time: They didn’t think it mattered to treat a fever until it was above 101º. But she did assert that she thought that fevers over 104º were dangerous, that they could cause “permanent brain damage,” and she’d seen many patients “go into fits” with high fevers. She considered it utmost important to lover the temperature past 104º.

The fits she was referring to seem to be the seizures the Seattle Children’s Hospital article is talking about, the ones the article said were concerning to look at, but not as worrisome as you’d think. I’m tempted to believe the article and the extent evidence over my mother about brain damage too.

Still, all within reason—be not unskeptical that seizures, fits, and high fevers are all good for you. But be interested in the evidence, that is suggesting that fevers up to 104º may truly be okay, and that even up to 108º won’t kill you, though once again—you really should be seeing someone at that point.

May you never have to make these decisions, and if you do, may you not have to make them alone.