The presence of fever has been documented for 4 million years, yet it continues to be one of the most misunderstood and misrepresented symptoms of all time.

Does fever serve a purpose? Should we treat fever and make it go away? In doing so, are we fixating on the messenger and not the culprit?

In the late 1970’s, some ill-fated iguanas found themselves in Matthew J. Kluger’s lab in Albuquerque New Mexico. Kluger injected these iguanas with a bacterium and the iguanas promptly developed fever. They were allowed to seek the warmth of sunlamps; all but one of the iguana’s sought out the warmth. The only iguana not to do so was the only iguana that died. Next (yes, there were more iguanas) Kluger not only injected the reptiles with the bacterium, but also gave them an antipyretic agent - lets just call it Igu-profen (or Igu-cetamol, Igu-dol, Igu-prin, take your pick). Only the iguanas that had breakthrough fever despite receiving Igu-profen, i.e. those with a strong febrile response to infection, were the ones to live.

The iguanas whose fever was “effectively controlled and treated” with Igu-profen, went to Igu-heaven. See his article aptly termed “Fever and Survival” on https://www.ncbi.nlm.nih.gov/pubmed/1114347/

There is more: Julius Wagner-Jauregg was awarded the Nobel Prize in Physiology or Medicine in 1927. In fact, this should have been a shared Nobel Prize between Wagner-Jauregg and Hippocrates - yes, from way back when. Hippocrates documented that patients who had “progressive paralysis” from syphilis had much improved symptoms after an unrelated febrile episode. Wagner-Jauregg takes this to another level: he finds patients with progressive paralysis of syphilis and gives them high fever...and what better to do this than by injecting malaria parasites into the bloodstream of the syphilis patients, right? So off they went, rigors and all, and a whopping 30% of patients had their syphilis symptoms improved (compared with the 1% natural remission rate). Ding ding! Nobel Prize. See https://www.nobelprize.org/ nobel_prizes/medicine/laureates/1927/wagner-jauregg-lecture.html.

Spurred on by these findings, Owens took patients with Gonorrhea and cooked them at 41.7C (107F) for 6 hours (PLEASE do not try this at home) using a hyperthermia chamber, curing a staggering 81%. See https://jamanetwork.com/journals/jama/article-abstract/274300?redirect=true

Children with chickenpox who were given antipyretic medications were noted to have more pocks and longer recovery times than the children who’s fever took a permissive approach, see https://www.ncbi.nlm.nih.gov/pubmed/2656959. Many other examples now support the approach of permissive fever, much like sweating it out like Grandma used to say. Imagine that....

As an infectious diseases specialist, I see thousands upon thousands of patients with fever. Fever is generated in response to an infection or inflammation, regulated by our body’s thermostat deep within our brains. In chemistry class, what did we do when we wanted a chemical reaction to go faster? We either shook it (a no-no when it comes to patients), changed its pH, or applied heat using a Bunsen burner. The hypothalamic set point changes - much like the thermostat of a central heater. After the desired peak and duration of fever is achieved, the thermostat shuts off, and the fever “breaks”. A typical febrile episode will resemble a graph with peaks and valleys. It is almost as if a certain amount of fever is called for in each case, much like the area under the curve (AUC). Once this quantity of fever has been generated, job done. This is why when fever is tightly regulated with the use of acetaminophen, ibuprofen or what have you, illnesses tend to drag on and on and on. Many times when patients come to me with 3 weeks of “on-and-off fever”, I tell them to stop treating it and start embracing it. Those that still choose to remain in my care thereafter (!!!) will have high fevers for 2 days (during which I endure their wrath), and then, almost like stepping off a ledge, the fever disappears, full recovery is achieved, and another believer is born.

The proponents of treating fever argue that during illness - a state of physiological stress - fever adds to the stress. It is also argued that fever is harmful to body tissue. Both of these are true, but only in certain conditions. Malignant hyperthermia, as occurs in certain medication induced fevers, carry an immense physiologic stress and should be treated. Fever can be harmful but only if sustained above 41 C (105.8F) or higher - sustained being the operative word, not when it is dipping in and out of that threshold. Most infectious fevers will fall in between 38.3C - 40C (101-104F).

There are two aspects for caution. Fever increases insensible (or invisible) fluid loss from the skin and respiratory tract by 1-2 liters a day. Hydration, therefore, is critical. The other issue relates to individuals prone to febrile convulsions (fever fits), usually children. Even in this situation, there is no clear evidence that preventative therapy with fever-reducing agents can reliably ward off febrile convulsions. See https://www.ncbi.nlm.nih.gov/pubmed/2656959, and http://adc.bmj.com/content/88/7/641, both from extremely reputable sources, the Cochrane database and the British Medical Journal group, respectively.

There are rare instances where the body is in a state of breakdown (catabolic states) as a result of massive trauma, burns and other severe systemic insults where controlling fever is metabolically advantageous - but these cases are almost always in intensive care, not in your bedroom plotting to get more screen-time.

So next time you have a fever - embrace it, don’t fight it. Drink plenty of fluids (but not gallons and gallons, see https://www.self.com/story/how-much-water-should-you-drink-when-youre-sick). Don’t reach for that tylenol, parasol, panadol, ibuprofen, neurofen or any other antipyretic du jour unless you are writhing in pain. Focus not on the fever but on recovering from the underlying cause.

I will add that I do walk the walk. I have 4 young humans at home, zero iguanas, and zero paracetamol. My youngest had fever fits when he was little, and after he turned 5 years old, I let him fly as far as fever was concerned. He’d touch a 105F, I’d hydrate him till his pee is near-clear, and he will make a safe landing 18-24 hours later, having naturally fought fire with fire. On one such occasion my mother implored: “Oh will you PLEASE take that child to see a real doctor!”

She too, at age 75, is now a believer. Keep Calm and Fever On.

I cannot stress the importance of severe illnesses such as meningitis, pneumonia and bloodstream infections being promptly evaluated by qualified medical professionals (I hate disclaimers but this one is important). No blog or website can ever replace the personal attention you will receive from a skilled physician.