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February 11 2021

Anatomy of a Fever: A Guide to Its Causes, Symptoms, and Treatment

A fever is one of the most common health conditions someone experiences when they are unwell, most commonly due to other illnesses. It is safe to say that most people have experienced it at some point, making it all too familiar.
However, a host of causes can lead to fever symptoms, one of which is an infection. With the SARS-CoV-2 virus still out there and the pandemic still ongoing, it is important to understand this condition. What happens to the body when a person has a fever? This infographic tells all.

Understanding Fevers: 10 Common Causes

A fever indicates that a person has become an infected host to a foreign invader, such as bacteria or virus. This causes a person’s body temperature to elevate above normal. If the recorded temperature reaches 38°C (100.4°F) or higher, the patient has a fever.
Since a fever is mainly a symptom of an underlying disease, it is essential to know that there are several and varied causes. Below are some of the most common:
1. Infection – When a person suffers from an infection, the body responds by attacking the foreign invaders to regain balance. Common examples of infections are influenza, pneumonia, or chickenpox.

2. Inflammatory diseases – Illnesses that cause inflammation in the body, such as rheumatoid arthritis (inflamed lining of the joints), can also cause fever because of the body’s innate response to draw increased blood flow to the inflamed tissue.

3. Autoimmune disease – An anomaly causes the immune system to view a person’s normal, healthy cells as foreign invaders, thus attacking it and treating it as an infection. An example of this condition is lupus, where the first few symptoms are fever, fatigue, and joint pain.

4. Certain medications – Some over-the-counter (OTC) medicines may have side effects, and fever could be one. This may not necessarily mean an infection, and it is more commonly reported in antibiotics or drugs that treat hypertension or seizures.

5. Immunization – Getting a fever is a normal side effect after receiving a vaccine, as the body is injected with an antigen that mimics the disease it is trying to prevent.
A fever is helpful in this case because it is a sign that the body is effectively developing sufficient antibodies to fend off any larger threats and achieve immunity. Fevers from immunization only last up to two (2) or three (3) days and are relatively harmless.
6. Heat exhaustion – Extreme dehydration or sunburn can cause a person's body temperature to rise—just like a device that is overheating. After replenishing fluids and resting, the fever will naturally go away.

7. Non-infectious agents – There are some cases when developing fever does not indicate infection. Some examples of these are having blood clots, hormonal disorders, and illicit drug use. Regular checkups with a doctor and a healthy lifestyle will prevent this.

8. Food poisoning – Infections are not always viral, as in the case of fever due to food poisoning. Ingesting raw, incorrectly prepared, or contaminated food or water can cause a person to invite bad bacteria into their gut, triggering the body's immune system response through a fever. A typical example is salmonella infection from undercooked chicken.

9. COVID-19 – The SARS-CoV-2 virus elicits a flu-like response in infected patients. As such, fever is one of the first symptoms those who develop COVID-19 get in the early few days of acquiring the illness.

10. Teething – In children and babies, teething can cause mild, low-grade fever that is not over 37.8°C (100°F). In most cases, young ones' body temperature should not spike high enough to cause a full-blown fever.

Accompanying Symptoms of a Fever

In most cases, fevers are accompanied by other symptoms that could help patients pinpoint their illness's underlying cause. More symptoms can appear if the fever is left untreated as well, such as:
  • Chills or shivering – It is common for a person with fever to feel cold. The higher their temperature is, the colder they will perceive their environment, even if they are in a warm area. Shivering or shaking may also be observed.
  • Sweating – To regulate the body temperature further, a patient may experience light to moderate perspiration, even if they report feeling cold.
  • Headache – General discomfort may lead to headaches or a heavy feeling in the head during a fever.
  • Nausea and vomiting – Some people report nausea or vomiting, especially in the case of food poisoning, as the body tries to get rid of the contaminant and irritant from the gut. Other times, this could be a symptom of another underlying health condition.
  • Loss of appetite – Food will not be the first thing on the minds of those who have a fever. Instead, it would be more beneficial to rehydrate their bodies. Water or soup are two great options for bringing back nutrients and hydration in a person with a fever.
  • Muscle aches – Most commonly observed in the flu, muscle aches accompany a fever as the body tries to fight the infection in the body.
  • Rashes – Getting red splotchy rashes all over the body could be the body’s manifestation of fighting moderate to severe infection. It could also be a symptom of dengue, which has fever and rashes as its top symptoms.

How to Treat a Fever

While trying to uncover the fever's underlying cause, the steps below may be followed to break the fever or keep body temperature from rising further.
  • Bed rest – The patient should catch up on a lot of sleep and rest and not engage in strenuous activities. Ensure the room is sufficiently warm, and they have a cold cloth over their forehead.
  • Hydration – Water helps regulate body temperature and replenishes fluids from sweating and vomiting.
  • OTC medication – Paracetamol, acetaminophen, and ibuprofen are the three most common medicines to bring down body temperature.
  • Lukewarm bath – Helping the body cool down can be achieved by a regular bath or a sponge bath using warm water.

Getting Down to the Bottom of a Fever

Fevers are not always black and white, so identifying its cause is still the best way to treat it. If the patient’s body temperature reaches over 39.4°C (103°F), it is imperative to seek immediate medical attention, especially for young children or if the fever persists. More severe symptoms that accompany this temperature reading are hallucinations or convulsions.
If you or your family members experience this, do not hesitate to reach out to Makati Medical Center for proper diagnosis of diseases stemming from fever and for other world-class professional health services.