A few days ago, some experts recommended that COVID-19 infected patients with fever and no sweating drink "brown sugar, green onion and white ginger soup" to reduce fever. Is this really useful? The answer of
is:
is useful if it is useful.
Because, after drinking, the body temperature will eventually drop.
However, from the perspective of the mechanism of fever, drinking "brown sugar, green onion and white ginger soup" is really useless.
To explain this issue clearly, I still need to start with the basic principles and processes of fever.
The principle and process of fever
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More specifically, it is released by the exogenous pyrogenic source that stimulates the body immune system Some inflammatory factors serve as endogenous pyrogens , the most important of which is prostaglandin E2, which can directly act on the heat-sensitive neurons of the hypothalamic body temperature center to upregulate the set target core body temperature, thereby causing the core body temperature to rise to the upregulated core body temperature through the body's energy-saving and/or energy-producing mechanism.
This means that the entire process of fever is carried out "step by step" under the control of the body temperature center, and the maximum temperature that can be reached is limited.
When the body temperature reaches the target temperature set by the hypothalamus, the body will activate the heat dissipation mechanism to automatically lower the body temperature.
As a result, the body temperature showed an obvious cyclical change process throughout the fever process.
This process is generally divided into a body temperature rising period, a plateau period and a body temperature falling period, and there may also be a certain intermittent period between cycles.
For example, the classic experimental fever body temperature in experimental guinea pigs using the bacterial pyrogen lipopolysaccharide (LPS) showed the typical periodic changes shown in the figure above. As can be seen in the
figure, although the experimental animals were not given any antipyretic drugs, the body temperature still dropped significantly, to a level close to the normal (baseline) level before fever.
Chills, heat and sweating without sweating during fever
At different stages of the fever process, patients will have different symptoms and signs.
In principle, the regulation of the body's core body temperature is similar to the automatic control of room temperature in a room where an automatic variable frequency heating and cooling air conditioner is installed.
The hypothalamic body temperature center is equivalent to the thermostat of the air conditioner. A fever is like us actively raising the set temperature of the air conditioner's thermostat, for example from the original 24 degrees to 28 degrees. The endogenous pyrogen prostaglandin E2 can also raise the set temperature of the body temperature center, for example from 37 degrees to 40 degrees.
At this time, the body temperature receptors in the hypothalamus still feel the actual 37 degrees, which is 3 degrees lower than the set target body temperature. This temperature difference will make the brain feel cold, thereby activating the mechanism of saving heat and/or generating heat to increase the body temperature. The energy-saving mechanism of
is to shrink blood vessels in the skin to reduce the temperature difference between the skin and the environment to reduce heat loss.
At this time, we not only feel cold, but our skin will also look pale and even get "goosebumps".
If the body temperature center "thinks" that this is not enough to raise the temperature in time, it will activate the heat production mechanism, which is shivering, and rapidly generate heat through muscle spasmodic contractions - the heat production efficiency of shivering is 500 times that of normal metabolism . The mechanisms above
will cause the body temperature to rise. This is the body temperature rising period during the fever process.
At this stage, the body feels cold, even shivering, and it is naturally impossible to sweat. This kind of body heat, chills, and no sweat during the fever and body temperature rising period is called "wind-cold syndrome" in traditional Chinese medicine, which does not understand the mechanism of fever.
When the actual body temperature rises close to or reaches the set target body temperature, the above-mentioned warming mechanism will terminate and the body will no longer feel cold.
Usually, the actual body temperature will fluctuate above and below the target body temperature for a period of time, which is the body temperature plateau period during the fever process.
If we use antipyretics to inhibit the production of prostaglandin E2, or the level of prostaglandin E2 acting on the body temperature center is reduced due to the own metabolism of prostaglandin E2, it will not be enough to maintain the originally set temperature.
The set temperature decrease will make the actual body temperature higher than the set temperature. Not only will we no longer feel cold, but we will feel warm to the point of being irritated, and the temperature center will start the cooling mechanism.
cooling mechanism also includes two levels. The first is to expand the skin blood vessels to increase the temperature difference between the skin and the environment to increase the heat dissipation speed. At this point, not only do we feel the heat, but our skin will also turn red.
If the set temperature is down too much, for example, a large dose of effective antipyretic drugs are used, and relying solely on skin blood vessel expansion is not enough to quickly cool down, the body temperature center will issue instructions, among which the rapid heat dissipation mechanism is sweating - sweating is an extremely efficient heat dissipation mechanism. Every 1 gram of sweat completely evaporates on the skin surface can take away 0.52 kcal of calories.
A lot of sweating will quickly take away a lot of calories, thereby causing the body temperature to drop rapidly.
This is the period of body temperature drop.
The higher the fever, especially after taking a lot of antipyretics, the faster the body temperature drops, the greater the sweating volume - although the actual mechanism is the opposite process.
This is what social media said recently that the principle of "smoking" in the quilt when the fever subsides - the evaporation of sweat under relatively high temperature and hunger humidity shows water vapor visible to the naked eye.
antipyretic drugs reduce fever by interrupting the fever process, while the sweating and fever reduction of "Brown Sugar, Onion, White Ginger Soup" is the greed for heaven
. As can be seen from the above, when we have a fever, we reduce fever by taking the activity of the prostaglandin synthetase cyclooxidase and inhibiting the production of prostaglandin, which is achieved by interrupting the physiological process of fever.
Since the absorption and effect of the drug take some time, the fever reduction effect after taking the medicine is lagging for a certain period of time.
But the antipyretic effect of enzyme cyclooxygenase inhibitors such as ibuprofen , acetaminophen has been verified by countless scientific experiments and clinical trials.
Why can drinking "Brown Sugar, Onion, White Ginger Soup" look like it can reduce fever?
In fact, whether it can reduce the fever depends on the time point of taking "Brown Sugar, Onion, White Ginger Soup" of .
If you drink "Brown Sugar Onion White Ginger Soup" during the rising body temperature period, it will not be possible to exert the effect of "reducing fever" in a short period of time;
If you drink "Brown Sugar Onion White Ginger Soup" in the later stage of the body temperature platform period, it will also "reduce fever" miraculous effect soon;
Of course, if you drink "Brown Sugar Onion White Ginger Soup" during the falling body temperature period when you have already started sweating, the "reducing fever" effect will be quite efficient.
Because, at this time, the ginger from ginger in "Brown Sugar and White Ginger Soup" and the sulfide from green onion are all sulfur-containing compounds like capsaicin , and can generate a heat and pain feeling by activating the capsaicin receptor.
Not only that, the capsaicin receptor is a multimodal receptor, which can also be 42 degrees high temperature (hot ginger soup), garlic, pepper, and almost all the "hot" medicinal materials considered by traditional Chinese medicine (mostly contain similar sulfur-containing compounds, such as cinnamon ), which can also stimulate the production of heat and pain .
This kind of heat pain can not have any effect at all during the rising temperature of the fever, but it can show its skills during the falling temperature of the body when the body is already warm. Just like eating chili peppers in the scorching sun, it will have a very efficient "cooling" effect of sweating.
Therefore, drinking (hot) "brown sugar, green onion, white ginger soup" can effectively reduce fever, but in fact it is just a greed for heaven.
