Viral infection or flu, how to tell the difference when you have a runny nose, cough, and fatigue
When it gets colder outside and coughing becomes more frequent on trams, the annual dilemma arises: cold or flu? At first glance, they may appear similar – a runny nose, sore throat, fatigue – but the difference often lies in the intensity, speed of onset, and how long it takes to return to a normal routine. And because there are many half-truths surrounding the term "cold", it's worth being clear about how to recognize symptoms, what can be handled with home treatment, when to see a doctor, and how to behave to prevent a common illness from becoming a problem for the entire family or colleagues.
Cold or flu: a difference worth knowing
The term "cold" is commonly used to refer to an acute viral respiratory infection – what is called a cold. It's caused by dozens of different viruses (often rhinoviruses, adenoviruses, and others), so one can encounter it repeatedly. The flu, on the other hand, is a specific illness caused by the influenza virus. This is where the difference between a cold and the flu begins: the flu typically has a more abrupt onset, more pronounced general symptoms, and more often "lays low" even an otherwise healthy person for several days.
With a cold, symptoms often develop gradually. A scratchy throat in the morning, a runny nose in the afternoon, a cough the next day, and a person tries to carry on – sometimes at the cost of unknowingly spreading the infection around. With the flu, it’s typical for the condition to deteriorate quickly: within a few hours, high fever, chills, muscle and joint pain, and significant exhaustion set in. It's not just a "stronger cold," but often a total hit to the body.
However, there are exceptions. The flu doesn't always mean extreme fevers, especially in older people, where the course can be atypical. And some colds can be unpleasant and prolonged. Therefore, it's useful to monitor a range of symptoms, not just one detail.
Try our natural products
How to recognize symptoms: what to look for
Simply put, a cold often starts "from the nose and throat," while the flu starts with "overall physical exhaustion." With a cold, a runny and stuffy nose is more pronounced and appears early. Sore throat, sneezing, and coughing alternate depending on where the infection settles. Fever may be just slightly elevated or sometimes absent.
The flu, on the other hand, often comes with a sudden fever (often 38–40 °C), chills, headache, muscle and joint pain, significant fatigue, and a feeling that "the body doesn't belong to the person." The cough is usually dry, irritating, and can be very unpleasant. Although a runny nose may appear, it's often not the main symptom in the initial days.
The ability to function can also be decisive. With a cold, someone might "push themselves" to go to work (which isn't ideal), while with the flu, it’s common for a person to truly remain bedridden because they lack the strength.
And what if someone isn't sure? A simple question helps: did it come on gradually, or like a bolt out of the blue? Even though it's not foolproof, this "shortcut" is often very typical of the flu.
Home treatment: what really helps (and what is a myth)
Whether it's a cold or the flu, treatment for most otherwise healthy people is mainly supportive. There is no universal pill that will "turn off" a viral infection. The purpose of home care is to relieve the body so it can handle the infection as best as possible without complications. It sounds simple, but in practice, rest is often underestimated.
The foundation is rest and sleep. During an infection, the body redirects energy to the immune response, and if a person tries to perform, they often risk a longer course or subsequent worsening. This includes plenty of fluids – with fever and rapid breathing, water is lost faster, and even mild dehydration worsens fatigue and headaches. Lukewarm teas, water, broths are practical; rehydration "in smaller doses but often" helps with fever.
Pain and fever are usually treated with common fever and pain medications (such as paracetamol or ibuprofen, depending on suitability for the individual). It's important not to overdo it with combining preparations – many "flu" mixtures already contain paracetamol, and carelessness can easily exceed the safe daily dose.
For a runny nose, nasal irrigation with saline solution and humidifying the air make sense. Nasal sprays for a stuffy nose can provide short-term relief, but they should not be used for long (typically no longer than a few days), as they can paradoxically worsen the nasal mucosa. For a sore throat, lozenges, lukewarm drinks, or gargling are usually pleasant.
Coughing is a chapter of its own. For a dry, irritating cough, humidifying the air, warm drinks, and sometimes short-term cough suppressants (again depending on the situation) can help. For a productive cough, the goal is to facilitate expectoration – plenty of fluids, warm showers, rest, and possibly expectorants help. It's not good to "shoot in the dark" and mix suppressive and expectorant preparations without thinking.
One thing is surprisingly effective yet often ignored: warmth, regular ventilation, and a simple routine. An overheated, dry apartment does not benefit mucous membranes, while slightly cooler and humidified air often relieves the nose and cough.
Home care also includes consideration for others. Infectious cold is not just an inconvenience for the individual but also a logistical problem for the family and workplace. Tissues, handwashing, ventilation, and limiting contact with at-risk individuals (seniors, chronically ill, newborns) are not excessive caution but sensible prevention of spreading.
"Antibiotics do not work on viruses – they are only useful for bacterial complications and always after a doctor's assessment."
This sentence is repeated every year and yet is still relevant. Not just because of effectiveness, but also because of antibiotic resistance, which is a long-term issue for organizations like the World Health Organization (WHO).
A real-life example: when "just a cold" changes plans for a week
In a typical household, it often starts innocently: a child brings a cold home from school, and the parents see it as a seasonal classic. The first two days are spent "at full speed" – work, activities, shopping. By the third day, the child is coughing more, the parent starts to feel a scratchy throat and fatigue sets in by evening. Instead of resting, they catch up on backlogs. Over the weekend, the other parent joins in, and suddenly one tissue turns into an entire box. By Monday, everyone feels exhausted, yet they try to "somehow function," extending the troubles – not necessarily because the virus is stronger, but because the body wasn't given a chance to rest.
This scenario is all too typical. It's not about moralizing, but rather a reminder that a few days of real rest can sometimes save a week of interrupted illness.
Duration of recovery from colds and flu: how long it takes and when to be cautious
The question of recovery time for colds and flu is among the most common – and the answer isn't entirely universal. However, there are general frameworks that help determine what is still a "normal course" and what deserves consultation.
For a common cold, it is often stated that the acute phase lasts several days, typically around 5–7 days. The runny nose and sore throat may be worst during the first three days, then the condition gradually improves. However, a cough can persist longer, sometimes even 2–3 weeks, because the mucous membranes heal slowly. This doesn't automatically mean a complication, but it's good to monitor whether the cough is improving or, conversely, worsening, accompanied by shortness of breath or fever.
The flu usually "comes quickly" and the worst phase may dissipate just as quickly – fever and major exhaustion often last 3–5 days. However, the return of energy can be slower. Fatigue, weakness, and reduced performance can drag on for 1–2 weeks, sometimes longer, especially if the illness is ignored. This is where the line is often drawn: once the fever drops, it's tempting to immediately jump back into full tempo, but the body may not yet be ready.
And what about infectiousness? With both colds and the flu, a person can be contagious even before full symptoms develop and for several days during the illness. It depends on the specific virus and the immune system, but it's generally reasonable to assume that infectious colds are most transmissible in the first few days. For the flu, contagiousness is often cited as roughly from the day before symptoms and several days afterward; for children and weakened individuals, it may be longer. Practically, this means that "it's already better" doesn't automatically mean "I won't infect anyone anymore."
When to see a doctor: clear signals it's time not to wait
Home treatment is sufficient in many cases, but there are situations where it's better not to play the hero. When to see a doctor?
Examination (or at least a telephone consultation) is advisable especially in the case of:
- shortness of breath, difficulty breathing, chest pain, wheezing or blue lips,
- high fever that can't be reduced, or fever lasting more than 3 days, or the return of fever after improvement,
- significant dehydration (little urination, great weakness, confusion),
- worsening condition instead of gradual improvement after several days,
- suspicion of complications (severe ear pain, sinus pain, purulent coughing with worsening, severe sore throat with swallowing difficulties),
- in at-risk groups – pregnant women, seniors, people with chronic heart, lung, diabetes, weakened immune systems – even with less dramatic symptoms.
For the flu, there are also antivirals that can be beneficial for some patients, especially in at-risk groups, but usually only when administered early. Therefore, it's worth not delaying if the course looks like the flu and the person falls into the risk category. Practical information on the flu and prevention is offered, for example, by the National Institute of Public Health: https://szu.cz/tema/prevence/chřipka/
Prevention: small habits that make a big difference
Prevention sometimes sounds boring, but in reality, it's the cheapest and most gentle "treatment" that exists. Moreover, it's not about perfection – just a few realistic steps that lower the likelihood of catching an infection or passing it on.
The foundation is hand washing (not just a quick rinse), because hands are the most common vehicle for viruses between the doorknob, the phone, and the face. Ventilation also makes sense, especially in crowded rooms where the air "runs out" quickly. During infection season, it helps to think about how often one touches their eyes, nose, and mouth – this is often how viruses enter.
Overall body condition plays a big role too. Sleep, regular exercise, and a sensible diet are not magical shields, but they provide a more stable foundation for the immune system. When combined with stress management and adequate fluid intake, the body often handles common infections more swiftly.
Specific prevention against the flu is vaccination, which is adjusted each year to circulating strains. It doesn't always mean 100% protection against infection, but it can significantly reduce the risk of a severe course and complications, which is crucial especially for at-risk groups and their close ones. Information on vaccination is consistently summarized by organizations like WHO.
And finally, there's a small thing that paradoxically is often the hardest: staying home when sick. It's not always easy, but from a public health perspective, it's one of the most effective forms of prevention. In practice, it's not just about "recovering quickly", but also about limiting the chain of transmission that could end up with someone for whom a common cold is no longer trivial.
So the next time the question arises, cold or flu, it's worth monitoring the course and intensity, giving the body rest, and not underestimating warning signals. And perhaps it's worth asking one simple rhetorical question: is it really worth "powering through it" when a few days of sensible routine might mean a quicker return to normal – and fewer tissues for everyone around?
