Cold, Flu or COVID-19?
Symptoms, Treatment and Vaccine Protection

At a glance

Common cold Generally mild, usually 5–7 days. Many different viruses (especially rhinoviruses). No vaccine available.
Flu (influenza) Often sudden onset, frequently high fever, strong feeling of illness. Annual vaccination recommended.
COVID-19 Variable course; long COVID possible. Annual booster recommended for certain groups.
RSV Particularly relevant for infants and seniors. Prophylaxis/vaccine available since 2024.
Distinguishing them Reliably usually only with a lab test (swab/PCR/rapid test) — not from symptoms alone.

Table of contents

  1. What are respiratory infections?
  2. Common cold
  3. Flu (influenza)
  4. COVID-19
  5. RSV
  6. Symptom comparison
  7. When to see a doctor? When to call emergency?
  8. Treatment and home remedies
  9. Protective measures and vaccinations
  10. How brite helps you
  11. FAQ
  12. Related topics

1. What are respiratory infections?

Acute respiratory infections are among the most common illnesses overall — many adults generally get several per year. They are mostly caused by viruses and affect the upper airways (nose, throat, larynx) and/or the lower airways (bronchi, lungs).¹

The four most important viral respiratory infections are: the common cold, the flu (influenza), COVID-19 and RSV. They are mainly transmitted through droplets or aerosols and occur more frequently in the autumn and winter months.¹

Important: symptoms alone are not enough for a diagnosis A reliable distinction between cold, flu, COVID-19 and RSV is generally NOT possible from symptoms alone — often only a lab test (swab/PCR/rapid test) brings clarity.

2. Common cold

Colds can be triggered by a wide variety of pathogens — frequently rhinoviruses, alongside seasonal coronaviruses (not SARS-CoV-2), adenoviruses and parainfluenza viruses. They are usually mild and generally clear up on their own within about a week.⁵

Typical symptoms

  • Runny nose (runny or blocked nose) — often the first symptom, frequently starts with tingling or sneezing
  • Sore throat — scratchy throat, difficulty swallowing (often in the first few days)
  • Cough — initially mostly dry, later often productive; can in some cases last several weeks
  • Mild fever or slightly elevated temperature (rarely very high in adults)
  • Mild headaches and general malaise
  • Generally rather gradual onset over 1–2 days
Duration and possible complications The main symptoms usually subside within a week. In risk groups (immunocompromised people, small children, seniors), complications can occur in some cases (e.g. bronchitis, sinusitis, middle-ear infections in children).

3. Flu (influenza)

True flu is caused by influenza viruses and often runs a significantly more severe course than a common cold. The Robert Koch Institute (RKI) estimates that, depending on the severity of the wave, anywhere from close to zero (mild seasons) to well over 20,000 excess deaths can occur (in very severe seasons such as 2017/18).¹ Older people and those with chronic conditions are generally particularly at risk.

Typical symptoms

  • Often a sudden onset — from relatively healthy to seriously ill within a few hours
  • Frequently high fever, chills
  • Strong feeling of being ill — many people describe it as feeling like they've been hit by a truck
  • Severe headache and body aches
  • Dry, painful cough
  • Pronounced fatigue and exhaustion — can in some cases last for weeks
  • Runny nose — generally less prominent in flu than in a cold
Possible complications Pneumonia, myocarditis (heart muscle inflammation), or worsening of chronic conditions such as asthma, COPD, diabetes or heart disease.¹
Risk groups (per Germany's STIKO) People aged 60+, people with chronic underlying conditions (airways, heart, kidney, metabolic), the immunocompromised, residents of long-term care facilities, and medical personnel.²
Antiviral therapy for flu (oseltamivir) For certain risk groups, antiviral therapy can be considered within roughly the first 48 hours after symptom onset. Prescription-only — the decision is always made by your treating doctor.

4. COVID-19

COVID-19 is caused by the SARS-CoV-2 virus. After the pandemic, SARS-CoV-2 has become one of the seasonal circulating respiratory viruses. Because of the now widespread immunity (from vaccinations and prior infections), most infections today run a comparatively mild course.³

Common symptoms (current variants)

  • Sore throat, runny nose, cough — often cold-like
  • Fever, headache, joint pain
  • Fatigue, exhaustion
  • Shortness of breath — particularly in more severe courses
  • Loss of taste or smell — less common with current variants than at the start of the pandemic, but still occurs
Long COVID Long-term consequences after COVID-19

Long COVID (also called post-COVID) refers to long-term consequences that can persist for weeks to months after the acute infection: e.g. persistent fatigue, concentration problems ("brain fog"), shortness of breath, sleep disturbances or palpitations. Long COVID can in principle affect any age group — including after mild courses. Vaccination and early antiviral therapy appear, based on current data, to reduce the risk.

Antiviral therapy for COVID-19 (Paxlovid) For certain risk groups, nirmatrelvir/ritonavir (Paxlovid) is available — within a few days of symptom onset. Prescription-only. Important: Paxlovid has numerous interactions — a medical and pharmacy review is always required before use. Learn more: Medication interactions.³

5. RSV (Respiratory Syncytial Virus)

RSV is often underestimated but is considered one of the most common causes of hospitalization in infants and can also lead to severe courses in seniors (e.g. pneumonia, worsening of existing COPD or heart failure).⁶

Typical symptoms

  • In adults: often cold-like (runny nose, cough, mild fever)
  • In infants: poor feeding, rapid breathing, nasal flaring, wheezing, and in some cases pauses in breathing
  • In seniors: often shortness of breath and worsening of existing lung or heart conditions
Protective measures against RSV (expanded since 2024) Nirsevimab (Beyfortus) — passive immunization, recommended by Germany's STIKO for all infants in their first RSV season.⁶
RSV vaccination for older adults — recommended by STIKO as a standard vaccination from a certain age and as an indication-based vaccination for relevant pre-existing conditions.⁶

In depth: RSV article.

6. Symptom comparison: cold vs. flu vs. COVID-19

Only as rough orientation — not a diagnosis A reliable distinction is generally only possible with a lab test. Doctor's offices increasingly have multiplex tests available that can detect influenza, SARS-CoV-2 and RSV from a single swab.¹
FeatureCommon coldFluCOVID-19
Onset Gradual (1–2 days) Often sudden (hours) Variable (1–3 days)
Fever Rather rare, low Frequently high Frequent, variable
Runny nose Dominant — key symptom Less prominent Frequent with current variants
Body aches Usually mild Often severe — typical Frequently occur
Feeling of illness Rather mild Usually severe, bed rest needed Variable
Loss of smell Only with congestion Rare Possible (currently less common)
Table scrolls to the right

7. When to see a doctor? When to call emergency services?

See your GP or out-of-hours medical service (116 117 in Germany)

  • High fever for more than about 3 days
  • Symptoms worsen after initial improvement (possible sign of a secondary bacterial infection)
  • Cough with yellowish-green sputum that persists
  • Earache — particularly in children (possible middle-ear infection)
  • You belong to a risk group (e.g. older age, chronic underlying conditions, immunosuppression)
  • In infants: poor feeding, rapid breathing, fever in the first six months of life
Call emergency services immediately (112 in the EU/UK, 911 in the US) for: Shortness of breath or breathlessness at rest, chest pain on breathing, impaired consciousness or confusion, bluish lips or fingernails (cyanosis), febrile seizure in children, pauses in breathing or persistent refusal to drink in infants.

8. Treatment and home remedies

Most respiratory infections clear up on their own. Treatment generally aims at relieving the symptoms.

General measures

  • Rest — with fever, bed rest as much as possible. No exercise until symptoms have fully resolved (among other reasons because of the risk of myocarditis)
  • Drink plenty — e.g. water, tea, broth. Fluid needs generally rise with fever
  • Humidify the air — dry indoor heating air can further irritate the mucous membranes
  • Stay home with symptoms and avoid contact with risk groups where possible

Medications for symptom relief

Fever and pain

Acetaminophen (paracetamol) or ibuprofen can be used for fever, headache and body aches. Important: in children and adolescents under 16, aspirin (acetylsalicylic acid / ASA) is generally not recommended because of the rare but dangerous Reye syndrome. Learn more: Medication before or after eating.

Runny nose

Saline (e.g. as a nasal spray or nasal rinse) is generally well tolerated. Decongestant nasal sprays (e.g. with xylometazoline) should only be used for a limited time to avoid rebound congestion (rhinitis medicamentosa).

Sore throat

Lozenges, warm or cool drinks, gargling with salt water or sage tea can help.

Cough

Inhalations with saline moisten the mucous membranes. Herbal expectorants (e.g. with thyme or ivy) are often used. Honey can be used as a home remedy in children from one year of age — in infants under one year, honey is off-limits because of the risk of botulism.

Antibiotics do NOT help against viral respiratory infections Cold, flu, COVID-19 and RSV are viral infections — antibiotics only work against bacteria. They are only prescribed selectively for bacterial complications (e.g. bacterial pneumonia, middle-ear infection). Unnecessary use can drive resistance. Learn more: How to take antibiotics.

Antiviral therapy (only for flu and COVID-19)

ConditionActive ingredientNotes
Flu Oseltamivir (e.g. Tamiflu) Generally within the first ~48 hours after symptom onset. Prescription-only. Only for risk groups.
COVID-19 Nirmatrelvir/ritonavir (Paxlovid) Numerous interactions — medical and pharmacy review is essential. Prescription-only. Only for risk groups.
Table scrolls to the right

9. Protective measures and vaccinations

General protective measures

  • Regular hand washing with soap — generally the single most important measure
  • Cough or sneeze into the crook of your elbow (not your hand)
  • Keep your distance from people who are ill
  • Stay home with symptoms — avoid daycare/school/work
  • Indoors, when respiratory viruses are circulating heavily, wearing a mask can make sense — particularly for risk groups
  • Ventilate regularly (e.g. open the windows wide for short bursts)

Flu vaccination (influenza)

Germany's STIKO recommends annual flu vaccination — generally in autumn (approx. October–November). Recommended among others for:²

  • Everyone aged 60+ — STIKO recommends from the 2025/26 season either a high-dose or MF59-adjuvanted vaccine²
  • People with chronic underlying conditions (e.g. airways, heart, kidney, diabetes)
  • Medical and nursing personnel and people with frequent public contact
  • Residents of long-term care facilities

COVID-19 vaccination

STIKO recommends an annual booster in autumn especially for:³

  • People aged 60+
  • People with relevant underlying conditions (e.g. lung, heart, kidney, diabetes, immunosuppression)
  • Medical and nursing personnel

For healthy adults under 60, STIKO generally considers basic immunity sufficient.³

RSV vaccination/prophylaxis

  • Nirsevimab (Beyfortus) — recommended by STIKO for all infants in their first RSV season as passive immunization⁶
  • RSV vaccination for older adults — as a standard vaccination from a certain age and as an indication-based vaccination for relevant pre-existing conditions⁶
Multiple vaccinations on the same day are possible Flu, COVID-19 and pneumococcal vaccines can typically be given on the same day per STIKO (then in different arms). Which vaccinations make sense in your individual case is decided by your treating doctor.²˒³

How brite helps you with respiratory infections

brite supports you from the first symptom to full recovery.

  • Health tracking — document symptoms day by day. Make the fever curve, cough duration, improvement or worsening easy to follow. Track your history
  • Medication reminders — painkillers, nose drops, oseltamivir or Paxlovid: brite reminds you on time. Set up a reminder
  • Interaction check — check cold medications against your regular meds, or Paxlovid against other drugs. Check now
  • Digital medication plan — all medications clearly laid out for GP, pharmacy and emergency department. Go to medication plan
Get started for free
brite app

FAQ: Common questions about respiratory infections

Generally not reliably — a confident distinction is usually only possible with a lab test (swab, rapid test, PCR). As a rough rule of thumb: sudden onset with high fever and a strong feeling of being ill points more toward flu. But there are also milder courses of flu and intense colds.
No. Cold, flu and COVID-19 are viral infections — antibiotics only work against bacteria. They are only used selectively for bacterial complications. Unnecessary use can drive resistance.
Germany's STIKO recommends annual flu vaccination especially for people 60+, those with chronic conditions and medical personnel. Beyond these groups, other adults can also be vaccinated. The individual decision is made by your treating doctor.²
Long COVID refers to long-term consequences after a COVID-19 infection — e.g. persistent fatigue, concentration problems, shortness of breath, sleep disturbances or palpitations. Long COVID can in principle affect any age group, including after mild courses.
For example: when high fever lasts longer than about 3 days, with shortness of breath, with chest pain, with marked worsening after initial improvement, or if you belong to a risk group. In infants, poor feeding, rapid breathing, or fever in the first six months of life are warning signs.
No — there is no vaccine against ordinary cold viruses, because many different pathogens are involved. An exception is RSV: since 2024, a prophylaxis for infants (nirsevimab) and vaccines for certain older age groups are available.⁶
With fever and acute infection, exercise is generally not advised — among other reasons because of the risk of myocarditis. Rule of thumb: only resume sport when symptoms have fully resolved. When in doubt, check with a doctor.
According to STIKO, simultaneous administration of flu and COVID-19 vaccines is generally possible (usually in different arms). A pneumococcal vaccine can also typically be given on the same day. The individual decision is made by the doctor.²˒³
The evidence is rather sobering: vitamin C may at most slightly shorten a cold, but a clear benefit is not established. Mega-dose intake once a cold has already started usually shows no clear advantage in studies. A balanced diet generally covers the vitamin C requirement.

12. Related topics

RSV (in depth) Asthma How to take antibiotics Medication before or after eating Medication and alcohol Medication interactions Missed medication

Sources

  1. Robert Koch Institute: RKI Guide on Seasonal Influenza and Weekly ARE Report. rki.de
  2. RKI: Influenza Vaccination — STIKO Recommendation (as of 2025). rki.de
  3. RKI: STIKO COVID-19 Vaccination Recommendation — Questions and Answers. rki.de
  4. STIKO (Germany's Standing Vaccination Committee) at the RKI — current recommendations. rki.de
  5. BZgA infektionsschutz.de — Pathogen profiles (common cold, influenza, COVID-19, RSV). infektionsschutz.de
  6. RKI: RSV Prevention with Nirsevimab and STIKO Recommendation for RSV Vaccination in Adults. rki.de
  7. gesundheitsinformation.de (IQWiG): Common cold. gesundheitsinformation.de
Medical disclaimer: This article is for general information only and is not a substitute for medical advice, diagnosis or treatment. Dosing and decisions about medications (e.g. antiviral therapies, antibiotics) are always determined individually by your treating doctor. With shortness of breath or other warning signs, call emergency services immediately (112 in the EU/UK, 911 in the US). In Germany, for non-urgent issues outside of office hours, the medical on-call service is reachable at 116 117. Last updated: April 2026.