Flu A: symptoms, dry cough, care and vaccine
Every winter, flu returns to Portugal. This guide explains the symptoms of flu A, how long a dry cough lasts, the warning signs, who should have the vaccine and what a video consultation can do for you.
The symptoms of flu A are those of seasonal flu: a sudden fever, feeling unwell, muscle aches, headache, a sore throat and a dry cough. According to the Directorate-General of Health (DGS), the name “flu A” comes from the 2009 pandemic and is no longer in use, because influenza type A viruses circulate every year. In healthy adults, flu clears up in 5 to 7 days, but the cough and tiredness can last up to two weeks. Shortness of breath, chest pain or confusion are warning signs.
Definition
What is now called flu A
Flu is an acute illness caused by the influenza virus, which mainly affects the respiratory tract. “Flu A” is flu caused by the influenza type A virus.
In 2009 a new type A virus, A(H1N1)pdm09, circulated for the first time and caused a pandemic because the population had no immunity. Since then, the DGS explains, the name “flu A” has stopped making sense: the A(H1N1)pdm09 and A(H3N2) viruses now circulate seasonally, alongside type B viruses.
In practice, anyone with “flu A” has seasonal flu. The symptoms, the care and the prevention are the same. Knowing whether the virus is type A or B rarely changes what you should do at home; the diagnosis is essentially clinical, based on symptoms and signs.
Flu occurs mainly between November and March. In recent years, the highest flu activity in Portugal has been seen between December and February, right in the festive season.
Source: Directorate-General of Health — Frequently asked questions about seasonal flu.
How it shows
Flu A: the most common symptoms
What sets flu apart is its sudden onset: a person feels well in the morning and by the afternoon has a fever and aching all over.
- Fever of sudden onset, often preceded by chills.
- Feeling unwell and marked tiredness.
- Muscle and joint pain.
- Headache.
- Pain on swallowing and an irritated throat.
- Dry cough, without phlegm at first.
- Sometimes, inflamed eyes.
Symptoms usually begin 1 to 3 days after contact with the virus. Unlike other upper respiratory tract infections, which start gradually and rarely cause a high fever or body aches, flu comes on suddenly and leaves the person exhausted.
Most symptoms improve after two or three days, although the fever can last up to five days.
Sources: DGS — Frequently asked questions about seasonal flu; MSD Manual — Influenza (flu).
After the fever
Dry cough and tiredness: how long they last
The fever passes in a few days, but the dry cough and tiredness are the symptoms that take longest to go away.
According to the DGS, in previously healthy people flu clears up in 5 to 7 days, except for the cough and fatigue, which can persist for up to two weeks. It is normal for the cough to get worse at night or in cold air, without this meaning a complication.
What is not normal is a cough that worsens after a few days of improvement, especially if the fever returns, or if shortness of breath or blood-stained or pus-containing phlegm appears. These are possible signs of pneumonia, the most common complication of flu, and call for medical assessment.
A dry cough that has not improved after two weeks, or that appears in someone with asthma, lung disease or heart disease, also deserves assessment, because flu can make these conditions worse.
Who needs more attention
Children, pregnant women and older people
In young children, older people and those with a chronic illness, recovery can take longer and the risk of complications is higher.
- Babies: fever and listlessness are the most common signs.
- Young children: vomiting, diarrhoea, laryngitis or bronchiolitis are common; middle ear infection is a frequent complication up to 3 years of age.
- Older children: symptoms are similar to those in adults.
- Older people, pregnant women, children up to 23 months and people with a weakened immune system: the illness can start more subtly and be more severe, with fatigue, confusion and, in rare cases, respiratory failure.
- Chronic illnesses: asthma, diabetes, and heart, lung or kidney disease can worsen during flu.
If you belong to one of these groups, or care for someone who does, it is worth speaking to a doctor in the first few days rather than waiting for the flu to pass on its own.
Source: DGS — Frequently asked questions about seasonal flu.
Transmission
How it spreads and how long you are infectious
The virus passes from person to person through droplets of saliva expelled when coughing and sneezing, and also via hands and contaminated surfaces.
- Incubation: about 1 to 3 days between contact and the first symptoms.
- Infectiousness: usually in the first 3 to 5 days of illness; it can be longer in children and in people with a weakened immune system.
- Protection: cough and sneeze into a paper tissue or your forearm, wash your hands often, air the home and reduce contact with other people while you have symptoms.
Source: DGS — Frequently asked questions about seasonal flu.
Treatment
What to do at home in the first few days
In most healthy people, flu treatment is rest, fluids and relief of the fever and aches.
- Stay at home and rest; do not wrap up too warmly.
- Take your temperature throughout the day.
- Drink plenty of fluids: water, tea, soup or fruit juice.
- For fever, the DGS mentions paracetamol, including for children. Do not give acetylsalicylic acid to children.
- Use saline solution to clear a blocked nose.
- If you are pregnant or breastfeeding, do not take any medicines without speaking to your doctor.
- If you live alone, ask someone to phone you regularly.
Antibiotics do not treat flu. They do not act on viruses, do not relieve symptoms or speed up recovery, and should only be taken with a medical prescription, when the doctor identifies a bacterial infection.
Antiviral medicines for flu exist, but they only work if started on the first or second day of symptoms. In a Cochrane review of clinical trials, oseltamivir shortened the time to first symptom relief by about 17 hours in adults (from 7 to 6.3 days). The decision to use them is a medical one and depends mainly on each person’s risk of complications.
Sources: DGS — Frequently asked questions about seasonal flu; Jefferson T et al., Cochrane Database Syst Rev 2014;(4):CD008965; MSD Manual — Influenza (flu).
When it is urgent
Warning signs that should not wait
Flu is, in most cases, a mild illness. Some signs, however, show that it may be developing into a complication.
A fever lasting more than five days, a cough with blood-stained or pus-containing phlegm, and the worsening of a chronic illness such as asthma or diabetes also call for a prompt medical assessment.
Prevention
Flu vaccine: who should have it
Annual vaccination is the main way to prevent flu, especially severe cases. The vaccine changes every year because the virus changes too.
The seasonal flu vaccination campaign for autumn-winter 2026-2027 runs from 30 September 2026 to 31 March 2027, according to DGS Norm No. 006/2026. Those eligible for free vaccination include:
- Children from 6 months to 4 years, inclusive. Children under 2 years who have never been vaccinated have two doses, at least four weeks apart.
- People aged 60 or over.
- Pregnant women.
- People aged 5 to 59 with risk conditions, such as diabetes, heart failure, chronic kidney disease, chronic respiratory disease, immunosuppression or severe obesity (body mass index of 40 or above).
- Residents of care homes and institutions, and some occupational groups, such as health professionals.
The vaccines used this season are trivalent and inactivated: they contain no live virus and therefore do not cause flu. As peak flu activity in Portugal has occurred between December and February, the DGS recommends vaccinating preferably before the end of the year.
If you do not know whether you belong to a risk group, or you are pregnant or have a chronic illness and have questions about the flu vaccine, our doctor can assess your situation and explain what applies in your case.
Sources: DGS — Norm No. 006/2026, updated 08/10/2026; DGS — Frequently asked questions about seasonal flu.
Festive season
Flu at holiday gatherings, visits and December travel
December brings several generations of a family to the same table, in closed, heated homes, in the month when flu tends to accelerate.
- If you have a fever, do not visit your grandparents or people with a chronic illness in the first days of symptoms, which is when you are most infectious.
- If you are hosting family, air the home several times a day and keep paper tissues and soap to hand.
- Get vaccinated in time if you belong to a risk group, ideally before the festive season.
- If you are travelling, avoid flying with a high fever and take your list of regular medication with you.
- If you fall ill away from home, a video consultation lets you speak to a doctor in Portuguese from wherever you are.
Video consultation
How our online consultation helps with flu
Flu is one of the reasons for which our video medical consultation was designed. You can book for the same day, without weeks of waiting.
- Assessment: the doctor reviews your symptoms, how many days ago they began, the fever, your breathing, chronic illnesses and the medication you already take.
- Warning signs: they identify what needs urgent examination and tell you clearly.
- Clinical plan: at the end of the consultation you receive a plan with the care to follow and what to watch for.
- Medical certificate: can be issued when clinically indicated, after assessment.
- Tests and referral: when necessary, our doctor refers you for blood tests, imaging or a specialist.
- Vaccine: they clarify whether you belong to a risk group and whether the flu vaccine makes sense in your case.
The consultation lasts 15 minutes, costs €39 and is carried out by a doctor registered with the Ordem dos Médicos. Some cases require a physical examination in person, for example to listen to the lungs; when that is so, the doctor tells you clearly and indicates the next step. Book your online medical consultation here.
Care in Portugal
Talk to a doctor about your flu
A video consultation lets you have your symptoms assessed, rule out warning signs and leave with a clear plan.
Fever, body aches and a dry cough?
Talk to a doctor by video today about your symptoms, the warning signs and the care to follow.
Sources
Sources for this article
Sources checked on 8 November 2026.
The article explains the symptoms, contagion, warning signs and flu vaccination. It does not recommend individual doses or treatments; that decision rests with the doctor, after assessing each case.
Questions
Frequently asked questions about flu
Flu A: which symptoms should lead me to see a doctor?
A fever lasting more than five days, a cough that worsens after a few days of improvement, blood-stained or pus-containing phlegm, or the worsening of a chronic illness call for medical assessment; our video consultation is a simple way to start. Shortness of breath, chest pain or confusion require immediate help.
How long does the dry cough of flu last?
The fever usually passes in a few days, but the dry cough and tiredness can last up to two weeks. A cough that has not improved after that time, or that gets worse, should be assessed by a doctor.
Can the flu vaccine cause flu?
No. The vaccines used in the seasonal campaign are inactivated and contain no live virus. After the vaccine you may catch other respiratory infections with similar symptoms, which the vaccine does not protect against.
Should I take an antibiotic for flu?
No. Flu is caused by a virus and antibiotics do not act on viruses. They are only useful if the doctor identifies a bacterial infection, such as some pneumonias.
For how long can I infect other people?
Usually during the first 3 to 5 days of illness. In children and in people with a weakened immune system, this period can be longer.
Can I get a medical certificate by video call?
Yes, when clinically indicated. The certificate is issued at the doctor’s discretion, after a full clinical assessment during the consultation.
