The most important thing first: with influenza A, most of what can change the outcome sits inside the FIRST TWO DAYS — and the thing that makes that difference is a prescription medicine that has to be prescribed by a doctor. If you are in a high-risk group, do not wait to see whether it settles by itself.
Recognising it: flu comes on suddenly, a cold builds up gradually
Influenza A opens sharply and hard: able to go to work in the morning, feverish, shivering and aching all over by the afternoon. With it come a dry cough, headache, sore throat, a blocked nose and a wrung-out exhaustion — and it is that exhaustion people remember most. Young children may vomit or have diarrhoea. Not everyone with flu has a fever. And nobody can tell it apart reliably by eye — the table below only gives the differences you can observe:
| Easily mistaken for | What you can see that differs |
|---|---|
| Common cold | Builds up over several days, worst in the nose and throat; less high fever, less body ache |
| Dengue | Turns severe exactly as the fever breaks; pain behind the eyes, possible bleeding from the gums |
| COVID-19 | Almost entirely overlapping; only a test tells them apart |
Who needs to see a doctor early rather than self-care at home
Healthy people who catch influenza A mostly recover on their own in about a week. But according to CDC, the groups below are more likely to become seriously ill — most commonly with pneumonia, and flu also makes underlying conditions worse:
- Children under 5, especially under 2.
- People aged 65 and over.
- Pregnant women, and anyone who has given birth within the past two weeks.
- People with chronic illness: asthma, lung disease, heart disease, diabetes, kidney, liver or neurological disease.
- People with weakened immune systems: cancer treatment, long-term corticosteroids, after an organ transplant, HIV infection.
- People with severe obesity; people living in long-term care facilities.
Why antivirals have to be prescribed by a doctor
According to CDC, flu antivirals can make the illness milder and shorter and reduce complications, but the effect is clearest when started within about the first two days of symptoms. So for someone at high risk, a doctor will often act straight away without waiting for a rapid test result. Because these are prescription medicines, only a doctor can establish whether this really is flu, whether the person belongs to a group that needs them, and whether they are safe alongside underlying conditions and current medicines. The name you will commonly meet is oseltamivir, usually called by the brand name Tamiflu. It is not a substitute for vaccination, and not everyone with flu needs it.
What to do at home straight away
- Write down on paper the DAY and the TIME symptoms started — a doctor asks about exactly this marker to know whether you are still inside the antiviral window, and it is often misremembered.
- Stay at home and genuinely rest. Pushing on at work with a fever means both a longer illness and infecting the whole office.
- Drink regularly, a little at a time: warm water, ORS mixed exactly as the packaging instructs, congee water, milk.
- Keep the patient in a separate room with their own towel and cup, with a mask on when leaving the room; everyone in the house washes their hands.
- Watch the things you can observe: is the breathing getting faster, are they still drinking, are they passing urine, are they alert or dull; with a young child, are they still playing.
- If a fever or pain needs treating, ask a doctor or pharmacist. Paracetamol (acetaminophen) is the usual choice, but how it is used is decided by a doctor.
What you must NOT do
- Do NOT buy antivirals yourself and do not use medicine left over from someone else: taken late or taken wrongly, you lose the window in which they still work.
- Do NOT buy antibiotics yourself: flu is viral. Antibiotics are only for when a doctor has established that there is also a bacterial infection.
- Do NOT give aspirin to children and teenagers with flu — according to CDC, aspirin in this group is linked to Reye's syndrome, a serious complication affecting the liver and brain.
- Do NOT take several over-the-counter cold remedies at the same time: many already contain paracetamol or aspirin, so adding another fever medicine means doubling up the same ingredient — read the label or ask a pharmacist.
- Do NOT wait overnight to see how things go once any of the warning signs below have appeared; and if you are in a high-risk group, do not wait for the fever to pass before seeing a doctor.
When you need to go in
GO TO EMERGENCY CARE NOW or call 115 (the emergency number in Vietnam) if any of the following appear. Adults: difficulty breathing or rapid breathing; persistent pain or heavy pressure in the chest or abdomen; confusion, hard to rouse; seizure; not passing urine; marked weakness or unsteadiness. Children: fast breathing, the chest drawing in, nostrils flaring; blue lips or face; muscle pain so bad the child refuses to walk; no urine for hours, dry mouth, crying without tears; not playing, not interacting when awake; seizure. A child under three months with a fever must be taken in straight away, with no waiting. At any age: A FEVER OR COUGH THAT HAD IMPROVED AND THEN GETS WORSE AGAIN, or an underlying condition that is deteriorating — go in, do not let it pass. — SEE A DOCTOR WITHIN 24 TO 72 HOURS if: you are in a high-risk group and symptoms have just started, because the antiviral window is narrow; a high fever persists without improving; marked exhaustion, a worsening cough, poor eating and drinking; a fever lasting more than three or four days. — If you are unsure, pregnant, or taking several medicines, call and ask before deciding yourself.
When to call a doctor to the house
Over these few days families usually need someone qualified for three things: whether this is really flu or something else, whether the patient belongs to a high-risk group, and listening to the chest so that pneumonia is not missed. A doctor or nurse coming to your home can do all three, and take test samples at home as well. But severe flu needing oxygen, continuous monitoring or a chest X-ray has to go to hospital — and once any of the warning signs above have appeared, go to hospital first and call afterwards.
The information above is based on publicly available US CDC material on influenza and does not replace being examined. Citing CDC here does not imply that CDC endorses Y Te Xanh or our services.
Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.
Sources
- CDC — About Influenza
