What is a Fever?
A fever is a condition where the body's temperature rises due to the body's immune response, causing the set point of the thermoregulatory center to be set higher than normal. While it is an important biological function that acts as a defense mechanism against infections and inflammation, depending on the symptoms, it can also be a sign of a serious condition.
Temperature Guidelines
| Temperature | Category | General Action |
|---|---|---|
| 〜37.4℃ | Normal to Mild Fever | Observation |
| 37.5〜37.9℃ | Mild Fever | Hydration, Rest |
| 38.0〜38.9℃ | Moderate Fever | Identification of Cause is Crucial |
| 39.0℃ and above | High Fever | Prompt Medical Attention |
*Normal body temperature varies from person to person, generally ranging from 36.0 to 37.0℃. Knowing your own normal temperature can help you notice changes in your health more easily.
How to Take Your Temperature Accurately
- Thoroughly wipe away sweat from the armpit.
- Place the tip of the thermometer in the center of the armpit hollow.
- Hold your arm firmly against your body.
- Avoid taking your temperature immediately after exercise, bathing, or eating (preferably after 30 minutes or more).
Main Causes of Fever
The causes of fever are extremely diverse. Most are caused by infections, but fever can also occur due to non-infectious diseases.
Fever due to Infection (most common)
| Condition | Characteristic Symptoms | Our Clinic's Response |
|---|---|---|
| Common Cold Syndrome | Runny nose, sneezing, sore throat, mild to moderate fever | Symptomatic treatment (antipyretics, antitussives, etc.) |
| Influenza | Sudden high fever, severe general malaise, joint pain | Rapid testing, anti-influenza drugs |
| COVID-19 | Sore throat, fever, loss of taste, malaise | Antigen testing, antiviral drugs (if applicable) |
| Streptococcal Infection | Severe sore throat, rash, red tongue | Rapid testing, penicillin antibiotics |
| Acute Gastroenteritis | Diarrhea, vomiting, abdominal pain, fever | Intestinal regulators, IV drip |
| Urinary Tract Infection (Cystitis, Pyelonephritis) | Fever accompanied by painful urination, frequent urination, lower back pain | Urinalysis, antibiotics |
| Pneumonia | Cough, sputum, difficulty breathing, high fever | Chest X-ray, blood tests, antibiotics |
| Acute Tonsillitis | Severe throat pain, difficulty swallowing | Examination, antibiotics |
Fever not caused by infection
- Heatstroke: Fever in summer or hot environments
- Autoimmune diseases (collagen diseases, rheumatoid arthritis, etc.)
- Hyperthyroidism (Graves' disease)
- Drug-induced fever (side effect of certain medications)
- Fever of unknown origin associated with malignancy
- Deep vein thrombosis, pulmonary embolism
When to Seek Medical Attention Promptly
Fever accompanied by the following symptoms requires caution
It may be a sign of a serious illness or worsening condition. We recommend seeking medical attention promptly without self-diagnosing.
- High fever of 38.5℃ or more that lasts for 2-3 days or longer
- Fever that does not subside even with over-the-counter antipyretics
- Severe headache, stiff neck, impaired consciousness
- Difficulty breathing, chest pain, decreased SpO₂
- Accompanied by painful urination, frequent urination, severe lower back pain
- Severe abdominal pain, diarrhea, or vomiting preventing fluid intake
- Rash appearing all over the body or spreading rapidly
- Fever after overseas travel (especially within 2 weeks)
- Fever in the elderly, pregnant women, or those with weakened immune systems
Tests and Treatments Available at Our Clinic
To determine the cause of the fever, we combine necessary tests according to your symptoms to make a diagnosis.
Rapid Tests (results in 10-15 minutes)
| Test | Target | Optimal Timing for Testing |
|---|---|---|
| Influenza Rapid Test | Type A, Type B | 12-24 hours after onset |
| COVID-19 Antigen Test | COVID-19 | Within 1-5 days after onset |
| Streptococcal Rapid Test | Group A β-hemolytic streptococcus | Immediately after throat symptoms appear |
| Combined COVID-19/Flu Test | Detects both at once | 12 hours after onset or later |
*Immediately after onset, there is a possibility of a false negative (negative result despite infection). We comprehensively evaluate test results, symptoms, and progression to make a diagnosis.
Blood Tests
We differentiate between bacterial and viral infections, assess the degree of inflammation, and evaluate organ function.
- White blood cell count (WBC) and differential: Neutrophils tend to increase in bacterial infections, lymphocytes in viral infections.
- CRP (C-reactive protein): Marker indicating the strength of inflammation.
- Liver function (AST, ALT), kidney function (BUN, Cr).
- Electrolytes (Na, K, Cl): Assessment of dehydration.
Urinalysis
Performed when urinary tract infections (cystitis, pyelonephritis) are suspected. We check for the presence of white blood cells, bacteria, and nitrites, and if necessary, identify the causative bacteria with a urine culture test.
Chest X-ray
If you have a cough, sputum, or shortness of breath, we check for the presence of pneumonia or bronchitis.
Intravenous Drip (IV Fluid Therapy)
For those who cannot take fluids due to vomiting or diarrhea, or those with severe dehydration, we replenish fluids and electrolytes via IV drip. Antipyretics and antiemetics can also be combined.
Home Care
Hydration is the Top Priority
During a fever, water loss from sweating and breathing increases, making dehydration likely. Hydrate frequently.
- Oral rehydration solutions (such as OS-1): Balanced in electrolytes.
- Sports drinks: High in sugar, so it's good to dilute them.
- Cooled boiled water, barley tea: Choose caffeine-free options.
Watch out for signs of dehydration
If you observe reduced urine output, dark urine, dry lips or mouth, or decreased skin elasticity (skin on the back of your hand stays tented when pinched), you may not be adequately hydrated.
Rest and Recuperation
Fever is a sign that your body is fighting infection. Don't overexert yourself; sufficient rest is the fastest way to recover.
Correct Use of Antipyretics
Antipyretics do not cure the fever itself, but rather aim to relieve uncomfortable symptoms and make it easier to rest and hydrate.
- Acetaminophen (Tylenol, etc.): Relatively safe for pregnant women, breastfeeding women, and children.
- Ibuprofen, Loxoprofen: Stronger effect but can cause stomach upset, caution with impaired kidney function.
Do not use aspirin for children under 15
Using aspirin-based antipyretics in children with influenza or chickenpox carries the risk of causing Reye's syndrome, a serious complication (encephalopathy, liver dysfunction). Always use acetaminophen.
Diet
There's no need to force yourself to eat if you don't have an appetite. Make sure to drink plenty of fluids and consume easily digestible foods (such as rice porridge, udon, soup, jelly, etc.) in small amounts. Avoid greasy foods, irritants, and alcohol.
Infection Control for Those Around You
If an infection is suspected, please pay attention to the following to prevent family transmission:
- Wear a mask and change it regularly.
- Frequent handwashing and gargling.
- Avoid sharing towels and dishes.
- Ventilate rooms (every 1-2 hours).
Features of Fever Treatment at Our Clinic
- Rapid testing for influenza, COVID-19, and strep throat (results in 10-15 minutes).
- Comprehensive diagnosis using blood tests, urinalysis, and chest X-rays.
- Prescription of IV drips, antiviral drugs, antibiotics, and antipyretics as symptoms require.
- Same-day visits possible without appointment.
- Clinic hours 9 AM to 9 PM daily, 1 minute walk from Jujo Station.
- Internal medicine and dermatology departments are co-located, providing one-stop care for skin symptoms such as rashes accompanying fever.
To patients visiting with a fever
To prevent infection of other patients, please call us or make a web reservation before your visit for smoother guidance. We also ask for your cooperation in wearing a mask.
