Every year, millions of people present with flu symptoms. Influenza, commonly known as the flu, is a viral respiratory infection that typically begins suddenly. It can cause fever, cough, sore throat, muscle aches, fatigue, chills, and headaches, notes Dr. Roxana Trejo González, Corporate Epidemiology Manager at Centro Médico ABC. Although some symptoms resemble the common cold, influenza is usually more severe and can lead to complications, especially in young children, older adults, pregnant women, and individuals with chronic health conditions.
How to Tell if You Have Influenza
Recognizing the early symptoms of influenza is one of the best ways to take timely action. Unlike the common cold, which develops gradually, flu symptoms in both adults and children appear unexpectedly.
To determine if you have influenza, pay attention to the following clinical signs:
- Sudden Onset: Symptoms appear abruptly from one moment to the next.
- High Fever: Typically accompanied by chills or a feverish feeling.
- Muscle Aches and Severe Fatigue: Deep exhaustion or fatigue that restricts daily activities.
- Respiratory Symptoms: Dry cough and persistent sore throat.
It is crucial to clarify that, because it shares symptoms with other respiratory infections, a definitive and accurate diagnosis of the influenza virus requires a medical evaluation or a laboratory diagnostic test.
Difference Between Influenza, the Flu, and a Cold
There is common confusion among these terms. It is important to clarify that "the flu" is simply the common, informal term for influenza. In contrast, the common cold is a different illness that is generally much milder.
While influenza impacts the body suddenly with high fever and intense fatigue, a cold begins gradually, characterized mainly by nasal congestion and frequent sneezing.
To help you identify your condition, you can refer to the following comparison table:
Feature |
Influenza (The Flu) |
Common Cold |
Onset |
Sudden | Gradual |
Intensity |
Higher | Lower |
Fever |
Frequent and high | Rare or mild |
Muscle Aches |
Common and severe | Mild or rare |
Fatigue |
Can be very intense | Usually mild |
Congestion & Sneezing |
May occur | Frequent |
Complications |
Can cause severe complications, especially in high-risk groups | Rarely causes serious health problems |
Types of Influenza and Symptoms
There are different variants of this respiratory disease. Influenza A and influenza B viruses are the primary causes of the seasonal flu epidemics that occur year after year.
- Influenza Type A: Highly common and includes well-known subtypes such as influenza A(H1N1) and A(H3N2).
- Influenza Type B: Occurs almost exclusively in humans and also circulates during winter seasons.
The symptoms of influenza A and B are clinically similar, so experiencing any of the mentioned signs warrants monitoring. Identifying the specific virus type is carried out using molecular or antigen tests when the treating physician considers it necessary for patient management.
When to Seek Medical Attention for Influenza Symptoms
In most cases, flu infections are mild; however, there is a risk of developing serious illness or severe complications, such as pneumonia, bronchitis, sinusitis, ear infections, or inflammation of the heart, brain, or muscle tissue (myocarditis, encephalitis, myositis, and rhabdomyolysis). Additionally, it can worsen chronic underlying health conditions like asthma.
Seek immediate emergency medical care if you experience any of the following warning signs:
In Adults:
- Difficulty breathing or shortness of breath (dyspnea).
- Persistent pain or pressure in the chest or abdomen.
- Confusion, ongoing dizziness, or inability to wake up easily.
- Seizures or convulsions.
- Fever or cough that improves temporarily, but then returns or worsens.
- Significant worsening of pre-existing chronic conditions.
In Children:
- Rapid breathing or severe trouble breathing.
- Bluish lips or face (cyanosis).
- Signs of dehydration (no tears when crying, dry diapers).
- Lack of interaction, lethargy, or unresponsiveness.
- High fever, or any fever in infants under 12 weeks of age.
Treatment for Influenza: When to Consult a Doctor
For mild cases, complex medical treatment for the flu is generally not required, and a person can recover with home care. Initial recommendations include absolute rest, continuous hydration, and staying home to break the chain of transmission and prevent spreading the virus.
To manage symptoms such as pain or fever, medications can be used under medical advice. In select cases—especially for high-risk individuals (newborns, adults over 65, pregnant women, or patients with chronic conditions)—a specialist will evaluate the use of specific antiviral drugs. It is crucial to note that antibiotics should never be used to treat the flu unless a doctor identifies a secondary bacterial co-infection, as antibiotics do not combat viruses.
How to Prevent the Flu
The most effective and safe way to prevent influenza and avoid its complications is annual vaccination. Because vaccine-induced immunity wanes over time and the virus mutates constantly, receiving the updated dose each flu season is essential.
In addition to vaccination, the following preventive hygiene measures are recommended:
- Wash hands frequently with soap and water, or use alcohol-based hand sanitizer.
- Cover your nose and mouth when coughing or sneezing using the inside of your elbow ("respiratory etiquette").
- Avoid close contact with anyone exhibiting symptoms of respiratory infections.
- Stay home if you are sick.
- Wear a face mask in enclosed or crowded spaces if clinical context or high local transmission rates warrant it.
At the Preventive Medicine Department at Centro Médico ABC, we offer specialized care. Contact us today!
Frequently Asked Questions
Fuentes:
Dra. Dra. Roxana Trejo González – Gerente Corporativa de Epidemiologia y Control de Infecciones del ABC
OMS, CDC, PAHO
