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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Yes, usually. Video assessment, symptom relief and, for some viruses, antiviral treatment.
- Antibiotics: they do not work against viruses; most viral infections clear on their own within 1 to 2 weeks.
- Antivirals: exist for only a few viruses, such as flu, COVID-19, shingles and herpes, and work best when started early.
- See a doctor: if a fever lasts more than 3 days, you get worse instead of better, or you are pregnant, over 65 or have a weakened immune system.
- Emergency: call 112 for difficulty breathing, confusion, a rash that does not fade under a glass, or a stiff neck with fever.
Do not book a video appointment if you are struggling to breathe, feel confused or very drowsy, have a rash that does not fade when you press a glass against it, a stiff neck with a severe headache, or blue, pale or blotchy skin. These can be signs of sepsis or meningitis: call 112.
Can an online doctor treat a viral infection?
Yes. Most viral infections, such as colds, flu, COVID-19 and stomach bugs, are diagnosed from your symptoms and the way the illness has developed, and a doctor can assess both by video. The doctor checks for signs of a bacterial infection or a complication, helps you ease the symptoms, and prescribes an antiviral medicine where one helps. Signs of sepsis or meningitis need emergency care instead.
Listen: Viral Infection Treatment Online
The audio version of this topic from the Mobi Doctor podcast. Open the episode.
How an online consultation helps with a viral infection
- Virus or bacteria?: The doctor weighs the pattern of your symptoms to tell a viral illness from a bacterial one, so you get antibiotics only when they will help.
- Antivirals when they make a difference: Antiviral medicines for flu, COVID-19, shingles and cold sores work best when started early, so the doctor checks first whether you would benefit.
- Warning signs ruled out: Breathing problems, dehydration and the signs of sepsis and meningitis are checked first, so a serious illness is not missed.
- A realistic recovery plan: You leave knowing how long the illness usually lasts, how long you are contagious, and when to get help again.
What the doctor checks in an online viral infection consultation
The consultation follows a fixed order, and the emergency signs come first. The doctor asks about:
- Emergency signs: difficulty breathing, confusion, a rash that does not fade under a glass, a stiff neck, or blue, pale or blotchy skin.
- Where the infection is: nose and throat, chest, stomach and bowels, skin, or the whole body.
- The timeline: when it started, whether you are getting better or worse, and whether a fever went away and came back.
- Fluids: how much you are drinking, any vomiting or diarrhoea, and how often you pass urine.
- Your risk: pregnancy, being over 65, a weakened immune system, long-term heart, lung or kidney conditions, recent travel, and anyone ill around you.
Before the call, take your temperature, note when each symptom started, and have your medicines to hand. If you have a rash, find good light so the doctor can see it on camera.
What are the symptoms of a viral infection?
A viral infection is an illness caused by a virus, a tiny germ that can only multiply inside the body’s own cells. Viruses cause most everyday infections, nearly all of them are contagious, and the symptoms depend on where the virus settles:
- Nose, throat and chest: a runny or blocked nose, sore throat, cough, fever and aches, as with a cold, flu, COVID-19 and RSV.
- Stomach and bowels: nausea, vomiting, diarrhoea and stomach cramps, as with norovirus and other gastroenteritis.
- Skin: blisters or a rash, as with cold sores, shingles and chickenpox.
- Whole body: fever, tiredness, swollen glands and aching muscles, as with glandular fever.
Many viral infections also bring a headache, a poor appetite and tiredness. A fever is part of the body’s normal response to infection. In adults, how unwell you feel, how well you are drinking and whether you are getting better matter more than the exact number on the thermometer. Some viral infections cause no symptoms at all.
Viral or bacterial infection: what is the difference?
Viruses and bacteria can cause very similar symptoms, but they are treated differently: antibiotics kill bacteria and have no effect on viruses. Doctors tell them apart from the pattern of the illness, and sometimes with a test.
Swipe sideways to compare →
| Sign | More likely viral | More likely bacterial |
|---|---|---|
| Where the symptoms are | Several areas at once: nose, throat and chest | Focused on one place, such as one ear, the tonsils or one side of the chest |
| Course | Worst in the first 2 to 3 days, then steadily improving | Getting worse, or improving and then worsening again |
| Fever | Usually settles within 3 to 5 days | Lasts longer, or comes back after settling |
| Green or yellow mucus | Common, and normal | Common too; colour alone proves nothing |
| Typical examples | Colds, flu, COVID-19, most coughs and sore throats, most stomach bugs | Strep throat, pneumonia, urine infections, some sinus and ear infections |
Some viral infections are followed by a bacterial one, such as a chest infection after flu. The warning sign is a fever that returns, or a cough or pain that gets worse after you had started to improve. Examples of bacterial infections include strep throat, pneumonia and urine infections. When the picture is unclear, a throat swab or a blood test for inflammation can help.
How long does a viral infection last?
Most viral infections clear on their own within 1 to 2 weeks, and you usually start to feel better after 3 to 5 days. Some take longer, and a cough or tiredness often outlasts everything else.
Swipe sideways to compare →
| Infection | Usually lasts | What often lingers |
|---|---|---|
| Common cold | 7 to 10 days | A cough or blocked nose for up to 3 weeks |
| Flu | About a week | Tiredness and a cough for 1 to 2 weeks more |
| COVID-19 | A week to 10 days | Tiredness and a cough for a few weeks |
| RSV | 1 to 2 weeks | A cough for several weeks |
| Norovirus | 2 to 3 days | Tiredness for a few days |
| Glandular fever | 2 to 3 weeks | Tiredness for weeks, sometimes months |
| Shingles | The rash heals in 2 to 4 weeks | Nerve pain for weeks in some people |
Feeling tired and low for a week or two after a viral illness is common. Tiredness that lasts more than 6 weeks, or gets worse after activity, deserves a doctor’s review, because it can be post-viral fatigue or another condition that needs attention.
Which viruses are going around?
In Europe, the common viruses follow the seasons. In autumn and winter, flu, RSV and COVID-19 circulate together and can reach high levels, alongside rhinovirus, the main cause of colds, and other cold viruses such as adenovirus, parainfluenza and human metapneumovirus (hMPV). COVID-19 also comes in waves outside the winter, because it has no settled seasonal pattern.
The flu tracker shows how much flu is going around, with separate trackers for COVID-19 and RSV. The contagious calculator works out how long you are likely to be contagious with flu, COVID-19, RSV, norovirus, strep throat or a cold.
What kills a stomach virus?
No medicine kills norovirus or the other stomach viruses: the body clears them, usually within 2 to 3 days, while you replace the fluids you lose. To stop them spreading, wash your hands with soap and water, because alcohol hand gels do not kill norovirus, wash soiled clothes and bedding at 60°C, and clean toilet seats, flush handles, taps and door handles.
Which viral infection treatment might the doctor recommend?
Treatment depends on the virus, how unwell you are and your risk of complications. This is the decision framework the doctors use, aligned with NICE and European guidance.
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| Cold-like symptoms or a viral sore throat | Rest, fluids, paracetamol or ibuprofen | Usually yes | If you get worse after a week, or become breathless |
| Flu symptoms within 48 hours, in someone at higher risk | Assessment for an antiviral such as oseltamivir | Usually yes | If you are breathless, confused or cannot keep fluids down |
| COVID-19 within 5 days, in someone at higher risk | Assessment for nirmatrelvir with ritonavir | Usually yes | If you are breathless at rest |
| A shingles rash, ideally within 3 days of it appearing | Antiviral tablets and pain relief | Usually yes, with photos of the rash | If the rash affects your eye or your vision |
| Vomiting and diarrhoea | Fluids and oral rehydration salts | Usually yes | If you cannot keep fluids down, or see blood |
| Fever with a non-fading rash, stiff neck or confusion | Emergency care | No | Call 112 now |
Not sure whether your infection is viral or bacterial? A doctor can tell you in one consultation.
See available times →Treatment options for viral infections
What you can do yourself
- Rest, and drink enough that your urine stays pale. With vomiting or diarrhoea, oral rehydration salts from a pharmacy replace the salts you lose.
- Take paracetamol or ibuprofen for fever and aches, at the dose on the pack, and do not take two products that both contain paracetamol. Ibuprofen does not suit everyone, including people with a stomach ulcer, kidney problems or heart failure, or anyone who is pregnant.
- Ease a sore throat with warm drinks, honey and lemon or salt-water gargles, and a blocked nose with a saltwater spray.
- Wash your hands often and stay at home while you have a fever. After vomiting or diarrhoea, stay off work until 48 hours after it has stopped.
Prescription treatment
A prescription is never issued without a consultation. Antiviral medicines exist for only a few viruses, and they work best when started early. The doctor may prescribe oseltamivir for flu in people at higher risk, ideally within 48 hours of the first symptoms; nirmatrelvir with ritonavir for COVID-19 in people at higher risk, within 5 days; and aciclovir or a similar antiviral for shingles, ideally within 3 days of the rash appearing, or for cold sores and genital herpes. If the signs point to a bacterial infection, the doctor may prescribe an antibiotic instead. If the doctor prescribes, use the prescription at a pharmacy near you.
What does not help
Antibiotics do not work against viruses. Taking them for a viral infection does not speed recovery, brings side effects such as diarrhoea and feeling sick, and adds to antibiotic resistance. Supplements sold to boost immunity have little good evidence behind them, and strong painkillers such as codeine are not prescribed online.
Special situations
Viral infections in pregnancy
Some viral infections matter more in pregnancy, including flu, COVID-19 and chickenpox. If you are pregnant and have a fever or a rash, or have been near someone with chickenpox or measles, speak to a doctor promptly. Paracetamol is the usual choice for fever and pain.
A weakened immune system
If your immune system is weakened by treatment or illness, viral infections can be more severe and last longer, and antivirals are used more often. Contact your specialist team as well as speaking to a doctor, and do not wait to see whether it settles.
Over 65 or living with a long-term condition
Viral infections can upset diabetes, heart failure and lung disease, and in older adults new confusion or a fall can be the first sign of an infection. Speak to a doctor early, and ask which of your usual medicines to keep taking while you are ill.
A fever after travel
A fever after travel outside Europe needs prompt assessment, because it can be malaria or another infection picked up abroad, and suspected malaria needs an urgent blood test. Tell the doctor where you have been and when.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When a viral infection is treated online, and when you need in-person care
Treated online: colds, flu, COVID-19, viral sore throats and coughs, stomach bugs without dehydration, cold sores and shingles, checks on whether an antiviral or an antibiotic would help, and advice on recovery and returning to work.
In-person care: difficulty breathing, dehydration, signs of sepsis or meningitis, shingles affecting the eye, suspected pneumonia that needs an examination, blood tests for a fever that will not settle, and any fever after travel to a malaria area.
When to get in-person care
Call 112 or go to an emergency department now for:
- difficulty breathing, or breathing very fast
- confusion, slurred speech, or being very drowsy or hard to wake
- blue, pale or blotchy skin, lips or tongue
- a rash that does not fade when you press a glass against it
- a stiff neck, a severe headache that keeps getting worse, or pain when looking at light
- a first seizure (fit)
Get medical advice the same day for:
- a high temperature that has lasted more than 3 days, or keeps coming back
- being unable to keep fluids down, or passing very little urine
- symptoms that improved and then got worse again
- a fever if you are pregnant, have a weakened immune system or have recently been in a malaria area
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CET. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about your symptoms: say when each one started and how it has changed, and show any rash on camera in good light.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Not sure it’s a viral infection? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Not sure this is the right page? Look up any symptom in the full symptom checker, or book and describe it to a doctor.
Frequently asked questions about viral infections
What is a viral infection?
A viral infection is an illness caused by a virus, a tiny germ that can only multiply inside the body’s own cells. Viruses cause most colds, coughs, sore throats and stomach bugs, as well as flu and COVID-19. Most viral infections clear on their own, and antibiotics do not work against them.
What causes a viral infection, and how do you catch one?
A viral infection starts when a virus enters the body, usually through the nose, mouth or eyes, and takes over cells to multiply; respiratory viruses arrive in droplets and aerosols from coughs, sneezes and talking and on hands that touch the face, stomach viruses on contaminated hands, food and surfaces, and others through blood, sex, insect bites or skin contact. Symptoms appear after an incubation period of 1 to 14 days depending on the virus, and most people are infectious before they feel ill.
What are the symptoms of a viral infection?
The symptoms of a viral infection depend on where the virus settles. Respiratory viruses cause a runny nose, sore throat, cough, fever and aches; stomach viruses cause nausea, vomiting and diarrhoea; and some viruses cause a rash or blisters. Tiredness, headache and a poor appetite are common with most.
How long does a viral infection last?
Most viral infections clear on their own within 1 to 2 weeks, and you usually start to feel better after 3 to 5 days. A cough or tiredness can last a few weeks. A fever lasting more than 3 days, getting worse after starting to improve, or symptoms lasting more than 3 weeks need a doctor’s review.
What are some examples of viral infections?
Common viral infections are colds, flu, COVID-19, RSV, norovirus and other stomach bugs, chickenpox and shingles, cold sores, glandular fever and measles. Hepatitis B and C and HIV are also caused by viruses.
How can I tell if an infection is viral or bacterial?
Viral infections usually affect several areas at once, peak in the first few days and then steadily improve. Bacterial infections are more often focused in one place, keep getting worse, or come back after you had started to recover. Green mucus alone does not mean bacteria. A doctor can weigh the signs, and sometimes a test helps.
Do antibiotics work on viral infections?
No. Antibiotics only kill bacteria and have no effect on viruses such as colds, flu and COVID-19. Taking them for a viral infection does not help you recover faster, causes side effects such as diarrhoea, and adds to antibiotic resistance.
Is a viral infection contagious?
Most viral infections are. Respiratory viruses spread through coughs, sneezes and hands, and stomach viruses through contaminated hands, surfaces and food. You are usually most contagious in the first few days. Stay at home while you have a fever, and for 48 hours after vomiting or diarrhoea has stopped.
How can I prevent viral infections?
Wash hands with soap for 20 seconds, especially before eating and after being out, keep hands away from your face, ventilate rooms, stay home when ill, cough into tissues, do not share cups or towels, clean surfaces during stomach bugs, and keep vaccinations up to date: the yearly flu vaccine, COVID-19 and RSV vaccines where offered, and the childhood and travel vaccines that prevent measles, hepatitis and more. Sleep, exercise and not smoking also make a viral infection less likely and milder.
What is the best treatment for a viral infection?
Rest, plenty of fluids, and paracetamol or ibuprofen for fever and aches help most people recover from a viral infection. Honey and saltwater sprays ease a cough and a blocked nose. Antiviral medicines exist for only a few viruses, including flu, COVID-19, shingles and herpes, and they work best when started early, so if you are at higher risk, see a doctor promptly.
What can I do at home for a viral infection?
Rest, drink enough that your urine stays pale, take paracetamol or ibuprofen for fever and aches, use honey, warm drinks and saline sprays for a cough and blocked nose, eat small amounts when you can, keep rooms ventilated, and stay away from others while feverish. A viral infection should be improving within a week; a fever lasting more than 3 days, getting worse after improving, breathlessness or a non-fading rash means seeing a doctor rather than waiting.
Which viruses are going around in winter?
In autumn and winter, the viral infections flu, RSV and COVID-19 circulate together across Europe, along with rhinovirus and other cold viruses such as adenovirus, parainfluenza and hMPV. COVID-19 can also come in waves at other times of year.
What kills a stomach virus?
No medicine kills norovirus or the other viral infections of the stomach; the body clears them, usually within 2 to 3 days. To stop the spread, wash your hands with soap and water, because alcohol hand gels do not kill norovirus, wash soiled laundry at 60°C and clean toilets, taps and door handles.
Can an online doctor treat a viral infection?
Yes. A doctor can assess most viral infections by video, check for signs of a bacterial infection or complication, and prescribe an antiviral medicine when one would help. You can use the prescription at a pharmacy near you. Emergency signs need in-person care.
When is a viral infection an emergency?
A viral infection is an emergency when it affects breathing, the brain or the circulation: call 112 for difficulty breathing or breathing very fast, confusion, unusual drowsiness or being hard to wake, lips or skin that look blue, grey or mottled, a rash that stays when a glass is pressed on it, a stiff neck with a severe headache and dislike of light, a first seizure. A high temperature on its own is not an emergency in an adult.
- Respiratory tract infections (RTIs), NHS, National Health Service (UK), 2024.
- Suspected acute respiratory infection in over 16s: assessment at first presentation and initial management (NG237), NICE, National Institute for Health and Care Excellence, 2023, updated 2025.
- Antibiotics, NHS, National Health Service (UK), reviewed 11 November 2022.
- Antibiotics: factsheet for the general public, ECDC, European Centre for Disease Prevention and Control, published 2 September 2021.
- Acute respiratory infections in the EU/EEA: epidemiological update and public health recommendations, ECDC, European Centre for Disease Prevention and Control, 2023.
- Shingles, NHS, National Health Service (UK), reviewed 23 November 2023.
- Myalgic encephalomyelitis (or encephalopathy)/chronic fatigue syndrome: diagnosis and management (NG206), NICE, National Institute for Health and Care Excellence, 2021.
- Sepsis, NHS, National Health Service (UK), 2026.
- Viral infection, Cleveland Clinic, reviewed 23 November 2022.
- Norovirus, NHS, National Health Service (UK), reviewed 31 December 2024.
- Do I have flu, COVID-19 or a cold? Know the signs and symptoms, UK Health Security Agency blog, 8 October 2025, updated September 2026.
- Coronavirus disease (COVID-19) fact sheet, WHO, World Health Organization, 27 November 2025.
- Adult with a viral illness, Gateshead Health NHS Foundation Trust, updated 11 December 2024.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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