Cold, Flu, Infection

The terms cold, flu, and influenza are often used to describe respiratory infections, even though they correspond to separate pathological conditions. Accurate distinction between them is essential for proper management and prevention.

The available tests for Cold, Flu, Covid, and other respiratory pathogens can be found at the bottom of the page.

Cold, Flu, Infection

What is a Cold?

The common cold is a viral infection that primarily affects the upper respiratory tract, including the nose, throat, sinuses, and windpipe. It is caused by more than 200 different viruses, with rhinoviruses being the most common. Colds are highly contagious and spread through airborne droplets or contact with contaminated surfaces. Unlike more serious illnesses, colds are usually mild and self-limiting.

Cold Symptoms?

Cold symptoms usually appear 1–3 days after exposure and include:

  • Runny or stuffy nose
  • Sore throat
  • Cough
  • Sneeze
  • Mild headache or body aches
  • Low-grade fever (rare in adults, usually <38°C)
  • Fatigue or feeling unwell

Symptoms peak within 2–3 days and gradually improve.

What is the Flu?

Influenza (the flu) is a contagious respiratory illness caused by influenza viruses (types A and B cause seasonal epidemics). It infects the nose, throat, and sometimes the lungs, leading to more severe symptoms than the common cold. Influenza can cause mild to severe illness and, in some cases, lead to hospitalization or death, especially in vulnerable groups.

Flu Symptoms?

Flu symptoms start suddenly and may include:

  • High fever (often above 38°C, up to 39–40°C)
  • Chills and sweats
  • Severe muscle or body aches
  • Headache
  • Dry cough
  • Sore throat
  • Runny or stuffy nose
  • Intense fatigue
  • In some cases, nausea or vomiting (more common in children)

Symptoms may last longer and lead to complications such as pneumonia.

What are respiratory viral infections?

The term virus is used generally for any viral respiratory infection (including colds and flu), without specific pathogen identification (as well as for viral infections other than respiratory).

How Long Do Colds and Flu Last?

The common cold usually lasts 7–10 days, peaking around days 3–5. The flu usually goes away in 3–7 days, but fatigue can persist for weeks. Both can last longer in some cases, especially if complications develop. You are most contagious for the first 3–4 days.

Colds and Flu in Children?

In children, colds and flu present similarly but are often more severe due to developing immune systems. Symptoms include fever (38.5–40°C), cough, runny nose, irritability, decreased appetite, and fatigue. Influenza can lead to higher risks of complications such as ear infections or hospitalization. Children under 5 years of age are particularly vulnerable.

Colds and Flu: Transmission & Prevention

Colds and flu are usually transmitted through droplets from coughing or sneezing, direct contact with infected people, and indirectly through surfaces such as doorknobs, telephones, or keyboards, where viruses typically survive for up to 48 hours.

The common cold is usually contagious 1-2 days before and 2-5 days after symptoms appear, while the flu can be contagious 1 day before and up to 7 days after symptoms appear (or 10-14 in children and immunocompromised people).

To prevent both, washing hands with soap or using a disinfectant (e.g. 0.1% bleach, 70% alcohol) with at least 60% alcohol helps, as does avoiding touching your eyes, nose and mouth, covering your cough with your elbow or tissue, regularly cleaning surfaces with disinfectant and ensuring good ventilation of rooms.

Especially for influenza, the annual vaccine from September-October offers 40-60% protection and is particularly recommended for vulnerable groups, while isolation at home for at least 24 hours after the disappearance of fever without medication, and the use of a mask in crowded places significantly reduce the risk of transmission.

Cold and Flu Treatment?

Treatment focuses on relieving symptoms:

  • Rest and hydration
  • Analgesics such as paracetamol or ibuprofen
  • Decongestants for nasal congestion
  • Antitussives or expectorants
  • Antiviral drugs for flu if started early
  • Home remedies such as honey (for children over 1 year old), steam inhalation, or saline nasal washes

Consult a doctor for severe symptoms or fever above 38.5°C that lasts >3 days or worsens, difficulty breathing, or any other symptom that causes you serious concern or worsens rapidly.

Most Common Viruses & Bacteria That Cause Cold, Flu Symptoms

Category Pathogen Main Symptoms Duration Season
Ιοί – Κρυολόγημα Ρινοϊός Runny nose, stuffy nose, sneezing, mild sore throat 5–7 days All year round
SARS-CoV-2 Fever, cough, loss of taste/smell 7–14 days All year round
RSV Cough, wheezing, shortness of breath 7–10 days Winter
Parainfluenza (1–4) Hoarseness 5–7 days Autumn
Adenovirus Sore throat, conjunctivitis, fever 7–14 days Year-round
Viruses – Influenza Influenza A / B High fever, myalgia, dry cough 3–7 days Winter
Bacteria Streptococcus pyogenes Severe sore throat, plaques, fever, no rhinitis 3–5 days Year-round
Streptococcus pneumoniae Sinusitis, otitis, pneumonia >7 days Winter
Haemophilus influenzae Purulent sinusitis, otitis >7 days Winter
Mycoplasma pneumoniae Dry cough, fever, “atypical pneumonia” 1–3 weeks Autumn

Why do a test that includes both viruses and bacteria?

Similar symptoms: Viral and bacterial infections cannot be reliably distinguished based on history and clinical examination alone.

Treatment differs: If it is a virus, antibiotics are useless and unnecessary use contributes to the development of antibiotic resistance, while if it is a bacteria and antibiotics are not given, it may worsen.

Secondary infection: A viral infection can be complicated by a secondary bacterial infection due to a weakened immune system. It is common, potentially serious, but treatable if recognized early.

Useful Websites
National Public Health Organization (EODY)

 

Respiratory Pathogen Test - Molecular & Rapid Tests

(Select a package to see the included exams)
Rapid Test:
Faster (results in 15-30 minutes) but less accurate (usually detects infection when severe symptoms are present).
Rapid Coronavirus COVID-19 7€
Coronavirus SARS-CoV-2 (COVID-19)
Rapid Streptococcus10€
Streptococcus pneumoniae
Rapid COVID-19, FLU A/B, RSV 15€
Coronavirus SARS-CoV-2 (COVID-19)

Influenza A Virus (IFV A)

Influenza Β Virus (IFVB)

RSV (Respiratory Syncytial Virus)

Rapid COVID-19, FLU A/B, RSV, Adenovirus 20€
Coronavirus SARS-CoV-2 (COVID-19)

Influenza A Virus (IFV A)

Influenza Β Virus (IFVB)

Respiratory Syncytial Virus (RSV)

Human Adenovirus (HADV)

Molecular Tests:
Slower (results within the day) but more reliable (detects infection even when there are no symptoms).
Cold Check - Molecular Detection of 19 Respiratory Pathogens 80€
Coronavirus SARS-CoV-2 (COVID-19)

Influenza A Virus

Influenza Β Virus

Human Adenovirus (HADV)

Mycoplasma pneumoniae

Human Rhinovirus (HRV)

Respiratory Syncytial Virus (RSV)

Parainfluenza Virus (HPIV) I, II, III, IV

Human Metapneumovirus

Haemophilus influenzae

Streptococcus pneumoniae

Klebsiella pneumoniae

Staphylococcus aureus

Pseudomonas aeruginosa

Legionella pneumophila

Acinetobacter baumannii

Molecular Coronavirus COVID-19 30€
Coronavirus SARS-CoV-2 (COVID-19)
Molecular COVID-19, FLU 60€
Coronavirus SARS-CoV-2 (COVID-19)

Ιός της γρίπης Α (IFV A/Influenza A Virus)

Ιός της γρίπης Β (IFVB/Influenza Β Virus)

Molecular COVID-19, FLU, RSV 80€
Coronavirus SARS-CoV-2 (COVID-19)

Influenza A Virus (IFV A)

Influenza Β Virus (IFVB)

RSV (Respiratory Syncytial Virus)

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