What is flu?

Flu is an infection caused by the Influenza virus and typically has a sudden onset, with more intense symptoms.

Main characteristics:

  • High fever (usually above 38°C)

  • Body and joint pain

  • Headache

  • Intense fatigue (prostration)

  • Dry cough

  • Chills

A person often "feels like they've been knocked down" overnight. In some cases, especially in elderly people, children and those with comorbidities, it can progress with complications such as pneumonia.

What is a cold?

A cold is caused by different viruses (such as rhinovirus) and tends to be milder, with gradual progression.

Main characteristics:

  • Runny nose

  • Sneezing

  • Nasal congestion

  • Mild sore throat

  • Absent or low fever

  • Mild malaise

Unlike flu, a cold generally does not prevent daily activities.

Main differences in practice

  • Onset:
    Flu → sudden
    Cold → gradual

  • Fever:
    Flu → common and high
    Cold → rare or mild

  • Symptom intensity:
    Flu → more intense
    Cold → milder

  • Impact on the body:
    Flu → can cause great indisposition
    Cold → generally tolerable

⚠️ When is it important to seek medical evaluation?

Some signs deserve more attention, especially if you suspect flu:

  • High fever persisting for more than 3 days

  • Shortness of breath or difficulty breathing

  • Chest pain

  • Worsening of symptoms after initial improvement

  • Patients with chronic diseases, elderly or small children

💡 What to do?

In both flu and cold, treatment is mainly supportive:

  • Adequate hydration

  • Rest

  • Fever and pain control with prescribed medications

  • Avoid inappropriate self-medication (especially antibiotics)

Annual flu vaccination is one of the main forms of prevention, especially for at-risk groups.

Although flu and cold are common, understanding the difference helps recognise warning signs and prevent complications.

This content is for informational purposes and does not replace individualised medical evaluation. In case of doubt or persistent symptoms, seek a healthcare professional.

Dr Rebeca Soares Andrade. CRM-GO 39335