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Why fever occurs, and what to eat in fever?

Disease, Nutrition

Fever is one of the most common physiological disorders everyone must have had at any point in life or every year. But I always get a question about why fever occurs and what to eat in fever. My mind also wonders, other than feeling warm, what are the symptoms of fever.

I know you can resonate with me since, at least once, you must have had similar questions. So, what are we waiting for? Let’s find out about it in this article.

why fever occurs

What is fever?

Fever, also called pyrexia, is an increase in one’s body temperature above a set point regulated by the body’s thermoregulatory center, the hypothalamus.

The body maintains its temperature at ~37 0C, meaning the normal body temperature in Fahrenheit (F) is 98.6 degrees F. There could be a shift by plus or minus 0.5 0C throughout the day, depending upon the activity, like metabolic changes, sleep/wake cycle, hormone variability, running, etc. [1]

What temperature cause fever

Depending on the level elevation in body temperature, fever can be characterized as [2]:

Low fever: 37.3 to 38.0 C (99.1 to 100.4 F)

Moderate fever: 38.1 to 39.0 C (100.6 to 102.2 F)

High fever: 39.1 to 41 C (102.4 to 105.8 F)

Hyperthermia: Greater than 41 C (105.8 F)

Why fever occurs

Except for the Artic ground squirrel, all mammals are endothermic. Meaning can regulate their body temperature irrespective of fluctuations in external temperature to gain freedom and acquire a different environmental niche [4].

Humans are no exception; in fact, further specialization in the regulation of temperature elevates the temperature with an encounter of infections caused by bacteria, viruses, or any pathogens [5].

With an entry of a foreign infectious body, cellular components of immune cells induce fever for thermal sensitive effectors who coordinates the febrile response through complex molecular pathways acting as a systemic alert system and promoting immune surveillance [6].

Moreover, in fever, the elevation of temperature inhibits bacterial growth and increases the bactericidal effect of neutrophils.

body transformation

The other side of the story is that the elevation of temperature is costly for metabolism; hence, the bottom line is that fever is beneficial only to a certain level, but if fever persists, it may be fatal or lead to brain damage [4].

Viral upper respiratory tract infection (URTI) is a cause of fever in babies and young children (approx. 90%), and a high fever of more than 39.5 0C is associated with influenza A virus infection [8].

Tonsillopharyngitis and pneumonia are also caused by viral agents and is primarily a disease in children which may begin with fever, sore throat, swallowing difficulty, etc. [8]

Note: if you want to read the details of molecular pathways, then read “Anatomy & Physiology by KS Saladin.”

What are the symptoms of fever?

The main symptom of fever is an elevation in body temperature, but in the case of a low fever to a moderate fever patient may or may not spot the difference in body temperature if not checked with a thermometer. Hence, the patient can relate to the following specific or non-specific sensations [3]:

  • feeling warm
  • chills
  • fatigue
  • myalgias (muscle pain)
  • back pain
  • headache
  • diaphoresis (unusual sweating)

What to eat when you have a fever

“Humanity has but three great enemies: fever, famine, and war, and of these by far the greatest, by far the most terrible, is fever.” – William Osler

These words of William Osler are the mirror of the detrimental effect of fever on humankind, and we who survived the fever fear of the COVID-19 pandemic know it better.

However, according to Earn et al., suppressing fever in normal clinical settings might be good for the individual but at the population-level, since it increases the possibility of the spread of infection [10].

So, what can be better than boosting our immunity to fight fever before and after the cause of the fever with an intake of certain nutrients? So, let’s see what to eat with a fever and cold.

One of your most important friends, which is essential in fever, is water and electrolytes, as you may experience dehydration and fluid loss. Never miss them; drink plenty of fluids.

Coming back to nutrients, fever in the case of viral respiratory disease and viral cold, a vitamin C and D are highly advised to incorporate since there is evidence that vitamin D can prevent acute viral URTI and recently faced COVID-19 [8].

Hence, all the citrus fruits such as Orange, kiwi, lime, grapes, blackcurrant, parsley, cruciferous, pomelo, Mandarina, Vegetables (cabbage, savoy cabbage, and broccoli), and so on must be included in the diet. Especially fever during the COVID-19 pandemic, citrus fruits, especially since they contain phytochemicals like naringin and hesperidin, which were effective in preventing COVID-19 and assumed to have antiviral activity and were necessary to boost host immunity [9].

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Other micronutrients which can act as an immunity booster to fight against infection are vitamins A and E and minerals like iron, zinc, and selenium [11].

Vitamin A is crucial for the normal functioning of innate immune cells, and research is ongoing on the role of vitamin A supplements in COVID-19 treatment. Cod liver oil, liver, dried apricots, carrot, hot pepper, and pumpkins are some of the foods that can supplement vitamin A.

The seeds like Flax seeds & chia seeds, nuts, and oil derived from them are a high source of vitamin E, essential Omega-3 fatty acids, and a good source of minerals like selenium and zinc, which is also versatile and as easy as soaking in water and consuming [12].

Green smoothies containing green veggies, seeds, and nuts are highly beneficial since they have the required nutrients for recovery from fever and are easy to make and digest.

Coconut water can be a medium of rehydration along with minerals, and yogurt, a source of probiotics, will help you recover two days earlier than the days it takes to recover.

Herbal preparation, like leaf extract of Hedera helix (Ivy leaf) and hot Lemon grass (Cymbopogon citratus) tea, may be effective in the discomfort caused by viral cold and fever [7]. But don’t consider tea as the medium of rehydration.

Chicken soup (a source of protein) or vegetable soups, including vegetables high in Vitamins and minerals, will help the body in the recovery process.

The bottom line is to drink plenty of water or fluids like coconut water to rehydrate yourself and cook fresh and nutritious food for better faster recovery from the fever.


What is the normal body temperature in Fahrenheit?

98.6 degrees Fahrenheit is the normal body temperature

How to reduce fever in adults?

Drink plenty of water/fluids and electrolytes.
Take a sponge bath in cool water
Eat nutritious food

Fever in adults when to worry?

If the fever becomes higher than 101 F or persists for a long duration, an adult must worry and immediately consult the physician.

Written by

Sobin S. Gupta (MSc)

Sobin S. Gupta is a multifaceted professional—nutritionist, researcher, writer, and diabetes educator. She founded "Nutrition Meet," dedicated to educating the community on preventing and curing chronic diseases. With a passion for health and wellness, Sobin empowers individuals to take control of their well-being through informed dietary choices.

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