The virus arrives
About one to four days after exposure — two, on average — influenza takes hold in the lining of your nose, throat, and airways. That's where the cough, sore throat, congestion, and chest discomfort come from.
Influenza
What I want my patients to know about prevention, treatment, and when to get help.
01
Influenza is a serious virus.
In 1918, an H1N1 influenza virus caused one of the deadliest pandemics in recorded history.
An estimated 500 million people became infected, roughly one-third of the world's population. At least 50 million people died.
It is difficult to overstate how devastating a loss that was, especially coming on the heels of World War I, which had already killed millions of people and profoundly disrupted societies around the world.
And those numbers become even more staggering when you consider this:
There were only about
1.8 billion people on Earth.
Humanity took thousands of years to reach a population of roughly 1.8 billion. Then, in barely more than a century, we grew to more than 8 billion.
Now return to that 1918 number: 500 million infections. One out of every three humans alive. Read the CDC history of the 1918 pandemic.
Today is very different
We have vaccines, antiviral medications, antibiotics for secondary bacterial infections, modern hospitals, and intensive care. But influenza has not become harmless.
Influenza affects more than just your lungs. In a 2018 study published in the New England Journal of Medicine, hospital admissions for heart attack were about six times as frequent during the first seven days after laboratory-confirmed influenza as during control periods before and after the infection. Read the heart attack study.
Influenza also causes thousands of deaths each year. Since 2010, the CDC estimates that annual influenza deaths in the United States have ranged from about 6,300 to 52,000.
Current CDC flu activityLive weekly hospitalization data
Loading the latest CDC data…
Source: CDC National Healthcare Safety Network. Open the full CDC FluView report.
02
Inside your body
Why the flu makes you feel so awful.
Some of it is the virus. Most of it is your immune system doing its job.
Your immune system sounds the alarm
Immune cells detect the virus and release chemical signals called cytokines — a kind of internal alarm bell. They rally the rest of your immune system into action, and that same alarm is what triggers fever, aches, fatigue, and the feeling that you've been hit by a truck. The discomfort isn't a side effect of the war. It's part of the strategy.
Your body changes priorities
Fever turns up your body's internal thermostat on purpose: influenza replicates less efficiently at higher temperatures, and your immune cells work better too. Shivering is how you generate the heat to get there fast. Fatigue works the same way — it pulls energy away from everything else so your body can spend it all on defense.
The short version
Listen to your body.
- If you are tired, sleep.
- If you are thirsty, drink.
- If you are cold, get under a blanket.
- If you are sick, stop trying to power through it.
Your immune system has been dealing with viruses much longer than you have been answering email.
03
Flu season and vaccination
Vaccination is the best tool we have against influenza.
This year's options
The CDC recommends that everyone 6 months and older get a flu vaccine every year, with rare exceptions. This year brings more options than ever: standard-dose, high-dose, and live attenuated nasal spray vaccines, plus a newly FDA-approved mRNA vaccine for adults 50 and older.
Children between 6 months and 8 years old who have not previously received at least two flu vaccine doses need two doses this season, given at least four weeks apart. The previous doses do not need to have been given during the same or consecutive seasons. After that, one dose a year is enough.
| Type of vaccine | Who it is for | Pros and cons |
|---|---|---|
| Standard-dose | Most people 6 months and older | The most widely used option, with extensive experience across age groups. Cell-based standard-dose formulations and a separate recombinant vaccine are egg-free, although specific age approvals vary. Egg allergy, even if severe, is not a reason to avoid any flu vaccine. |
| High-dose | Adults 65 and older | Contains extra antigen to produce a stronger immune response in older immune systems. It can cause more soreness or achiness than a standard-dose vaccine. CDC also preferentially recommends adjuvanted or recombinant vaccines for this age group. |
| Live attenuated nasal spray | Healthy, non-pregnant people ages 2 to 49 | No needle, which can make vaccination easier for children and others who dislike injections. It uses weakened live virus, so it is not an option during pregnancy or immunocompromise. Asthma and certain chronic conditions may also make another vaccine a better choice. |
| mRNA | Adults 50 and older | Newly FDA-approved technology that may be easier to update quickly as influenza strains change. It is still building a real-world track record. For adults 65 and older, CDC's established preferred options are high-dose, adjuvanted, or recombinant vaccines. |
We do not always get every detail right. Sometimes the strains chosen months in advance turn out to be an imperfect match, but that is a long way from a random guess.
How strains are chosen
Influenza spreads more efficiently in cooler, drier conditions. Then people add another ingredient: we go inside. Windows close, schools are in session, and we spend more time breathing the same air.
When it is summer in New England, it is winter in the Southern Hemisphere. Their flu season occurs during our summer. That turns out to be medically useful.
Laboratories around the world collect and study circulating influenza viruses. Scientists track which strains are spreading and how they are changing. The World Health Organization reviews the data and issues separate vaccine recommendations for the Northern and Southern Hemispheres.
Want to nerd out? See how WHO chooses vaccine strains ↗Vaccine safety
The standard flu shot cannot give you influenza. It does not contain live influenza virus capable of causing infection or replicating in your body.
I think of it this way. The scene is an old Western town. The sheriff is putting up wanted signs. The outlaw is the flu.
The standard flu shot contains enough influenza antigen for your immune system to study the poster and build antibodies and immune memory, without ever meeting the real outlaw. Full protection takes about two weeks to develop.
Some people may feel achy or run a low fever after the shot. That is the town running a drill, the same kind of immune response your body uses against a real infection. It does not mean that the vaccine has infected your airways. The drill is not the actual robbery.
That is the whole point of the drill. If the real outlaw ever does ride into town, your immune system already has antibodies and white blood cells watching for it, ready to recognize it on sight and respond before it can cause as much trouble.
When to get vaccinated
For most adults, September or October is the sweet spot. Vaccinating too early can mean more waning by late winter. Waiting too long risks letting influenza arrive first. If October has passed, get vaccinated anyway while influenza is still circulating.
Current CDC vaccination recommendations · The 2026 to 2027 flu season · FDA information on the mRNA flu vaccine
Quick decision guide
Which flu vaccine should I get?
Open the vaccine advisor
04
Sleep
Sleep is not wasted time when you are sick. Your body is mounting an immune response. Give it the opportunity to work.
Drink
Water, tea, broth, ice chips, and oral rehydration drinks all count. Small, frequent sips can be easier when you feel nauseated.
Use saline
Warm salt-water gargles can soothe the throat. Nasal saline can loosen mucus. Use safe water for nasal irrigation.
Treat discomfort
You do not have to chase a modest fever if you are comfortable. But you do not earn bonus points for suffering.
05
Medicines: what helps and what does not
Know what you are treating and why.
AntiviralsMost important for higher-risk patients
Antiviral treatment is recommended promptly for people who are hospitalized, very sick, or at higher risk of serious complications.
People at higher risk include pregnant people, adults 65 and older, young children, people with certain chronic conditions, and people who are immunocompromised. If that describes you, call early. Do not wait for illness to become severe.
For otherwise healthy people with mild, uncomplicated influenza, most do not need an antiviral.
When started within the first one or two days, oseltamivir may make symptoms milder and shorten illness by about a day on average. That can be worthwhile for some people, but it is not a necessary treatment for everyone.
For severe, progressive, or hospitalized illness, treatment may still help even when more than 48 hours have passed.
CDC antiviral guidance ↗AntibioticsNot for the influenza virus
Antibiotics work against bacteria. Influenza is a virus and does not have the bacterial structures or processes that antibiotics target. So the antibiotics don't apply here.
Some antibiotics, including macrolides such as azithromycin, have anti-inflammatory effects in certain settings and may have made you feel better in the past. That does not make them a treatment for uncomplicated influenza and does not justify taking them “just in case.” The side effects and antibiotic resistance are real, while the influenza virus remains untreated.
That said, influenza can set the stage for a secondary bacterial infection, especially pneumonia. If you start to improve and then develop a new fever, worsening cough, shortness of breath, chest pain, or a major decline, call us. That is a reason to be examined.
Oxymetazoline nasal sprayWorks, but keep it short
It can provide excellent short-term relief from severe congestion. Repeated use for too long can cause rebound congestion. Think short term, generally no more than three days. For ongoing congestion, saline is much friendlier.
AntihistaminesRead the ingredients
Older antihistamines in many nighttime products can cause sedation, confusion, falls, dry mouth, constipation, and urinary retention. Those risks matter especially in older adults.
GuaifenesinFine if it helps
Guaifenesin is intended to make secretions easier to clear. Benefits may be modest and it can upset the stomach. Hydration matters too.
BenzonatateI am less enthusiastic
Evidence for acute cough is limited, and cough helps clear secretions. Accidental ingestion can cause severe toxicity in children. Often the better question is why you are coughing and whether postnasal drainage is driving it.
FDA safety information ↗06
Home remedies and myths
Feeling better is a valid outcome.
I like home remedies. I just distinguish between “this makes me feel better” and “this kills influenza.” Those are very different claims.
If warm tea soothes your throat, drink it. If your grandmother's soup makes you feel human again, eat the soup. If honey, ginger, apples, or a family tradition helps you rest and recover, and it is safe for you, I am not going to demand a randomized trial before you enjoy it.
Not everything that helps has to kill the virus.
Sometimes feeling better is enough.
Things I would not spend much money on
- Oscillococcinum: good evidence that it meaningfully prevents or treats influenza is lacking.
- Vitamin C after you are sick: fine in your diet, but not a proven influenza treatment.
- Zinc for influenza: discussed more for the common cold and not established as an effective flu treatment.
- Vitamin megadoses: correct real deficiencies. More is not automatically better.
Interactive tool
Build your flu comfort plan.
If you do get the flu (or other viral respiratory illness), use the tool below to manage symptoms, and decide when to reach out for help.
When to get help
Call early if you are high-risk.
Get urgent help for warning signs.
Contact your clinician promptly if you are pregnant, older, immunocompromised, have important chronic medical conditions, are very sick, cannot stay hydrated, or simply feel that something is wrong.
- Trouble breathing or shortness of breath
- Persistent chest or abdominal pain or pressure
- Confusion, severe dizziness, or difficulty waking
- Seizure
- Not urinating or severe dehydration
- Severe weakness or unsteadiness
- Improved, then returned with fever or a worse cough
- 01Get vaccinated.
For most people, September or October is a good target. Later is still better than never.
- 02If you are sick, stay home.
Do not donate your influenza to the community.
- 03Listen to your body.
Sleep. Drink. Rest. Get comfortable.
- 04Do not throw medicines at every symptom.
Understand what you are treating and why.
- 05If you are high-risk, call early.
Antiviral treatment is most useful when we do not wait.
- 06Warning signs mean get help.
Trouble breathing, chest pain, confusion, dehydration, or rapid worsening should not wait.
Your body is not doing nothing while you lie in bed feeling miserable. It is running an extraordinarily sophisticated defense operation.