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Flu (Influenza)

A contagious virus of the nose, throat and sometimes the lungs that tends to hit suddenly, with fever, aches and exhaustion. Most people recover in under two weeks, but flu can be serious — a yearly vaccine is the best protection.

Call 911 or go to the emergency room for any of CDC’s emergency warning signs of flu complications. CDC says people with these signs should get medical care right away (CDC) and that they are a reason to go to the emergency room (CDC).

In children:

  • Fast breathing or trouble breathing
  • Bluish lips or face
  • Ribs pulling in with each breath
  • Chest pain
  • Severe muscle pain (the child refuses to walk)
  • Dehydration (no urine for 8 hours, dry mouth, no tears when crying)
  • Not alert or interacting when awake
  • Seizures
  • Fever above 104°F that is not controlled by fever-reducing medicine
  • In children younger than 12 weeks, any fever
  • Fever or cough that improve but then return or worsen
  • Worsening of chronic medical conditions

In adults:

  • Difficulty breathing or shortness of breath
  • Persistent pain or pressure in the chest or abdomen
  • Persistent dizziness, confusion, or being unable to wake up
  • Seizures
  • Not urinating
  • Severe muscle pain
  • Severe weakness or unsteadiness
  • Fever or cough that improve but then return or worsen
  • Worsening of chronic medical conditions

CDC notes these lists are not complete: check with a provider about any symptom that is severe or concerning (CDC). If you are at higher risk (see below), call your provider early in your illness and remind them of your risk — antiviral treatment helps most when started within 2 days (CDC).

What is flu, and how common is it?

Influenza (flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat and sometimes the lungs. It can cause mild to severe illness, and at times death. Influenza A and B viruses cause the yearly epidemics, and flu vaccines are updated every year (CDC).

A 2018 CDC study estimated that, on average, about 8% of the U.S. population gets sick from flu each season, ranging from 3% to 11% depending on the season; children are the most likely to get sick (CDC). Some seasons are much harder. For the 2024–2025 season, CDC’s preliminary estimates are 51 million flu illnesses, 710,000 hospitalizations and 45,000 deaths — a high-severity season, the first since 2017–2018. People 65 and older accounted for 71% of the deaths, and 290 flu deaths in children were reported, the most for a regular flu season since reporting began in 2004 (CDC).

Flu or a cold?

Both are contagious respiratory illnesses caused by different viruses, and they can be hard to tell apart by symptoms alone. Flu is generally worse: symptoms are more intense and start more abruptly, while a runny or stuffy nose is more typical of a cold. Colds rarely lead to serious problems such as pneumonia or hospital stays; flu can (CDC). CDC adds that fever, aches (often severe), tiredness and headache are common with flu, but rare, slight or only occasional with a cold (CDC). Only a test can confirm flu (CDC). See our Common Cold guide.

Symptoms

Flu usually comes on suddenly, with some or all of: fever or chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and tiredness. Vomiting and diarrhea are more common in children than adults. Not everyone with flu has a fever (CDC). Symptoms usually begin about 2 days after infection (range 1 to 4 days) (CDC), and most people recover in a few days to less than two weeks (CDC).

Who is at higher risk?

Serious flu can happen at any age, but CDC lists these groups as more likely to have serious complications (CDC):

  • adults 65 and older, and young children — CDC highlights children under 5, especially under 2 (CDC);
  • people with asthma, chronic lung disease (such as COPD or cystic fibrosis), heart disease, past stroke, diabetes or other endocrine disorders, kidney, liver, blood or metabolic disorders, or neurologic and neurodevelopmental conditions;
  • people with a weakened immune system from disease (such as HIV or some cancers) or medicines (such as chemotherapy or long-term steroids);
  • people with a body mass index of 40 or higher, and people with certain disabilities, especially those who have trouble with breathing, coughing or swallowing;
  • people under 19 on long-term aspirin or salicylate medicines;
  • pregnant women, including up to 2 weeks after pregnancy ends (MBHA plans a separate Pregnancy guide);
  • nursing home and long-term care residents; and
  • non-Hispanic Black, Hispanic or Latino, and American Indian or Alaska Native people, who face a higher risk of flu hospitalization.

In recent seasons, 9 out of 10 people hospitalized with flu had at least one underlying health condition (CDC).

Complications: pneumonia and worsening of long-term conditions

Sinus and ear infections are moderate complications. Pneumonia is a serious one, caused by flu alone or by flu together with bacteria. Flu can also inflame the heart, brain or muscles and lead to organ failure or sepsis (CDC). Having flu raises the risk of pneumococcal disease (CDC), and CDC also lists bronchitis among flu complications (CDC). MBHA plans a separate Pneumonia guide; see our Bronchitis guide.

Flu can also make long-term conditions worse (CDC):

  • Asthma: flu can trigger attacks, and asthma is the most common condition among children hospitalized with flu (CDC). See Asthma.
  • COPD: chronic lung disease is on CDC’s higher-risk list (CDC). See Emphysema.
  • Diabetes: about 30% of adults hospitalized with flu have diabetes, and flu can push blood sugar up — or down if you can’t eat or drink as usual (CDC). See Diabetes.
  • Heart disease: about half of adults hospitalized with flu have it, and one study found heart attack risk was 6 times higher in the week after confirmed flu (CDC). MBHA plans a separate Heart guide.

How it spreads

Flu spreads mainly through droplets made when people with flu cough, sneeze or talk, which can land in the mouths or noses of people nearby; less often, from touching a contaminated surface and then your mouth, nose or eyes. People are most contagious in the first 3 days of illness, and the virus can be found in most infected people from 1 day before symptoms start up to 5 to 7 days after; young children and people with weakened immune systems may stay contagious longer (CDC).

Testing

Symptoms alone can’t confirm flu, and a provider may diagnose it without a test. Rapid antigen tests give results in about 10 to 15 minutes but can miss flu; rapid molecular tests take 15 to 20 minutes and are more accurate; lab tests such as RT-PCR are more accurate still. Some FDA-approved home tests check for flu and COVID-19 together. CDC has no specific guidance on home tests, but if you test positive and are at higher risk, contact your provider right away about antivirals. You can have flu and COVID-19 at the same time (CDC).

The yearly flu season

Flu viruses circulate all year, but U.S. flu season usually runs through fall and winter, most often peaking between December and February — and most often in February (CDC).

Bird flu (H5N1): what CDC says now

A(H5) bird flu is widespread in wild birds and is causing outbreaks in poultry and U.S. dairy cows, with sporadic human cases among dairy and poultry workers — 72 reported U.S. human cases since February 2024. CDC says the current public health risk is low (CDC). Most U.S. cases have been mild, no person-to-person spread has been found in the U.S., and no bird flu virus, including H5N1, has gained the ability to spread easily among people. Seasonal flu vaccines aren’t designed to protect against bird flu. Avoid touching sick or dead birds and animals, skip raw milk, and cook poultry, eggs and beef thoroughly (CDC).

Side by side

Six approaches compared

For every condition we look at the same six approaches: what each involves, what it typically costs, and what a patient can realistically expect.

ApproachWhat it involves Estimated costWhat to expect
Conventional medicine (AMA) A flu vaccine every season for everyone 6 months and older, with rare exceptions; prescription antivirals (oseltamivir, zanamivir, peramivir, baloxavir) for people at higher risk or very sick; rest, fluids and fever reducers. No aspirin for anyone 18 or younger; antibiotics don’t treat flu. Flu vaccine: $0 under Medicare Part B if your provider accepts assignment, and covered without a copay by Marketplace and many other plans in-network. Antivirals, tests and visits: cost estimate being researched. Most people recover in under two weeks. Antivirals work best started within 2 days and can shorten illness by about a day. Vaccination lowers the risk of flu and of serious illness.
Chiropractic No role in preventing or treating flu. Not applicable. A 2021 systematic review found no clinical evidence that spinal manipulation prevents infections or improves immune function. Reschedule visits while sick.
Acupuncture Not an established treatment for flu. Cost estimate being researched. We found little research, and no controlled trials, on acupuncture for flu. Reschedule appointments while sick.
Herbal medicine Elderberry, echinacea, vitamin C, zinc, probiotics and the homeopathic product Oscillococcinum are often tried. Never eat raw or unripe elderberries. Cost estimate being researched. NCCIH says no complementary approach has been shown to prevent flu or relieve its symptoms. Never use them instead of a flu vaccine, and check interactions with your pharmacist.
Massage therapy Don’t book a massage while you are sick or contagious. Cost estimate being researched. Massage doesn’t treat flu. Wait until you have recovered, to protect your therapist and their other clients.
MBHA Wellness Coach Handwashing, covering coughs, staying home until CDC’s return-to-activity test is met, sleep and fluids, masks as CDC describes, and a plan for higher-risk family members. Cost estimate being researched. Everyday habits lower the chance of catching and spreading flu. A coach supports — never replaces — vaccination and medical care.

Approach 1 of 6

Conventional medicine (AMA)

Most people with flu have mild illness and don’t need medical care or antivirals; rest at home and avoid others except to get care (CDC).

1. A flu vaccine every season

CDC says everyone 6 months and older should get a flu vaccine every season, with rare exceptions, and that it is particularly important for people at higher risk (CDC). See Flu vaccines: who, when and why below, including what changed for 2026–2027.

2. Prescription antivirals

CDC recommends four FDA-approved flu antivirals: oseltamivir (a pill or liquid), zanamivir (inhaled; not recommended for people with asthma or COPD), peramivir (given into a vein) and baloxavir (a pill; not recommended in pregnancy, while breastfeeding or in the hospital). They are prescription-only (CDC).

  • Start early. They work best when started within 2 days of getting sick, can shorten illness by about a day, and may reduce some complications. Starting later can still help people at higher risk or in the hospital (CDC).
  • Who needs them. CDC says to start them as soon as possible for people in the hospital, people who are very sick, and people at higher risk — for example with asthma, diabetes, heart disease or pregnancy. Most healthy people with mild flu don’t need them. Oseltamivir is the one recommended in pregnancy, and for children from birth (CDC).
  • Side effects include nausea and vomiting (oseltamivir), wheezing (zanamivir) and diarrhea (peramivir). Antivirals are a second line of defense, not a substitute for the vaccine (CDC). We don’t list doses here.

3. Comfort care at home

Rest and sleep, and drink plenty of water to avoid dehydration. Over-the-counter fever reducers and pain relievers — acetaminophen (called paracetamol in the UK), or a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen — can lower a temperature and ease aches. For a child, check the package to make sure the medicine suits them, or ask a pharmacist (NHS). Never give a child under 2 a cough and cold product containing a decongestant or antihistamine; these products are labeled “do not use in children under 4” (FDA). Many cold and flu products already contain acetaminophen, and too much can cause severe liver damage: don’t take more than one product containing it (FDA).

No aspirin for children and teens. CDC says no one 18 or younger who has or may have flu should be given aspirin or any salicylate product, such as Pepto-Bismol, because of the risk of Reye syndrome, a rare but very serious complication (CDC).

4. Antibiotics don’t treat flu

Antibiotics fight bacteria, not viruses like influenza. When they aren’t needed they won’t help, and side effects such as rashes, severe allergic reactions, resistant infections and C. diff diarrhea can still cause harm (CDC).

What it costs

  • Medicare: Part B covers the seasonal flu vaccine, usually once each flu season; you pay nothing if your provider accepts assignment (Medicare.gov).
  • Other insurance: Marketplace plans and many other plans must cover flu vaccines for adults and children without a copayment or coinsurance, generally from in-network providers; $0 isn’t guaranteed in every case (HealthCare.gov, HealthCare.gov).
  • Antivirals, flu tests and visits: cost estimate being researched.

How well it works — what to expect

When the vaccine matches the circulating viruses, it has cut the risk of a doctor visit for flu by 40% to 60% (CDC). CDC estimates that in 2024–2025 flu vaccination prevented about 10 million illnesses, 180,000 hospitalizations and 12,000 deaths (CDC).

Find a medical doctor in our directory

Approach 2 of 6

Chiropractic

Chiropractic care has no role in preventing or treating flu. Claims that spinal manipulation improves immune function rose sharply during the COVID-19 pandemic, but a 2021 systematic review found no clinical studies showing that it prevents infections or improves outcomes in people who have one, and no clinical evidence that it changes immune function (Chow et al., JAMA Network Open, 2021).

Keep up with your flu vaccine: in a national survey, children who had used manipulative therapies such as chiropractic were less likely to have had one (Bleser et al., Pediatrics, 2016). And reschedule visits while you have flu symptoms — CDC advises staying home and away from others (CDC).

Find a chiropractor in our directory

Approach 3 of 6

Acupuncture

We found little research on acupuncture for flu. A PubMed search turned up no controlled trials in people with flu; the closest was a 1992 report of 57 people with fevers from colds, flu, tonsillitis or bronchitis, with no comparison group described (Tan, J Tradit Chin Med, 1992). NCCIH says no complementary approach has been shown to prevent flu or relieve its symptoms (NCCIH). If you use acupuncture for other reasons, choose a licensed practitioner with sterile, single-use needles (NCCIH), and reschedule while you are sick.

Find an acupuncturist in our directory

Approach 4 of 6

Herbal medicine

NCCIH’s summary is plain: no complementary approach has been shown to prevent flu or relieve flu symptoms. Echinacea, elderberry, Oscillococcinum, vitamin C, vitamin D, American ginseng, green tea and Chinese herbal medicines have all been studied for flu without enough evidence to show whether they help (NCCIH).

Supplements don’t replace a flu vaccine. NCCIH says complementary approaches should never be used as a substitute for flu vaccination (NCCIH).

  • Elderberry: some preliminary research suggests it may ease flu or cold symptoms (NCCIH), but the evidence is low quality because only a few small studies exist (NCCIH). Raw or unripe berries, leaves and stems are poisonous and can cause nausea, vomiting and severe diarrhea; cooking removes the toxin. Safety in pregnancy and breastfeeding is unknown (NCCIH).
  • Echinacea: mostly studied for colds, where it may slightly lower the chance of catching one. It can cause allergic reactions, sometimes severe (NCCIH).
  • Zinc and vitamin C: the research is mostly about colds; zinc isn’t on NCCIH’s list of approaches studied for flu. Too much vitamin C can cause diarrhea and nausea, and zinc used in the nose has been linked to lasting loss of smell (NCCIH). See our Common Cold guide.
  • Probiotics: they might lower the chance of colds or flu, but the evidence is low quality (NCCIH), and they have been linked to dangerous infections in people with serious medical problems (NCCIH).
  • Oscillococcinum (homeopathy): no strong evidence that it prevents or treats flu (NCCIH). FDA has approved no homeopathic product, and homeopathic products should never replace immunizations (NCCIH).

Herb-drug interactions

Some herbs and medicines interact in harmful ways (NCCIH). American ginseng may interact with the blood thinner warfarin (NCCIH); for Asian ginseng, promoted for flu, there are open questions about interactions with some blood pressure, statin and antidepressant medicines (NCCIH). People with long-term conditions — the same people at higher risk from flu — often take several medicines, so check every product with your pharmacist. We don’t list doses here.

What it costs

Cost estimate being researched.

Approach 5 of 6

Massage therapy

Massage doesn’t treat or prevent flu. MBHA’s advice: don’t book a massage while you are sick or still contagious. A session means close contact for an hour or more, flu spreads mainly through droplets from coughing, sneezing and talking (CDC), and your therapist may also treat clients at higher risk. Wait until you meet CDC’s return-to-activity test (see the Wellness Coach section); therapists who are sick should stay home too (CDC).

Avoid deep or vigorous work while you are recovering. Rare serious side effects of massage have involved vigorous techniques such as deep tissue massage (NCCIH), and one case report described severe muscle breakdown and kidney failure with flu after a long deep-tissue massage — a single case that can’t prove cause (Dickey et al., case report, 2021).

What it costs

Cost estimate being researched.

Find a massage therapist in our directory

Approach 6 of 6

MBHA Wellness Coach

An MBHA Wellness Coach helps you build habits that make flu less likely to reach you, or to pass from you to someone more vulnerable. CDC calls a yearly vaccine the single best protection, with everyday habits adding to it (CDC).

  • Clean hands: scrub with soap and water for at least 20 seconds, especially after blowing your nose, coughing or sneezing, or use a sanitizer with at least 60% alcohol (CDC). Avoid touching your eyes, nose and mouth, and clean often-touched surfaces (CDC).
  • Cover coughs and sneezes, with a tissue if you must be around others while sick (CDC, CDC).
  • Sleep and fluids: CDC’s healthy habits include plenty of sleep, physical activity, managing stress, plenty of fluids and nutritious food (CDC). A coach can help you build a regular bedtime and plan easy sick-day meals.

Staying home, and when to go back

Stay home and away from others, including people you live with who aren’t sick. CDC says you can return to normal activities when, for at least 24 hours, both are true: your symptoms are getting better overall, and you haven’t had a fever without using fever-reducing medicine. For the next 5 days, take added precautions such as cleaner air, hygiene, a well-fitted mask, distance or testing. If fever returns or you feel worse, stay home again (CDC). CDC’s flu page adds that people with flu who have no fever should stay home from work for at least 5 days after symptoms start (CDC). A coach can help you plan cover at work in advance, as CDC suggests (CDC).

Masks, as CDC describes them

CDC calls a mask an extra layer of protection you can choose — helpful in crowded places, when illness is rising in your community, or when you or people around you are at higher risk. Worn by a sick person, a mask reduces spread; well-fitting masks also protect the wearer, and N95 respirators protect the most (CDC).

Planning for higher-risk family members

When tiredness lingers

People with ME/CFS often say their illness began with something like flu (CDC). If exhaustion lasts for months after an infection, talk with your provider and see our Chronic Fatigue & ME/CFS guide.

Another approach

Flu vaccines: who, when and why

Who

Everyone 6 months and older, every season, with rare exceptions (CDC).

  • Pregnancy: get a flu shot, not the nasal spray, at any stage. Vaccination in pregnancy is linked with lower flu risk for the mother and for the baby in the first months of life (CDC).
  • 65 and older: CDC prefers a high-dose, recombinant or adjuvanted vaccine; if none is available, any age-appropriate vaccine is fine (CDC).
  • Nasal spray: an option for many people aged 2 through 49, but not in pregnancy or with some medical conditions (CDC); people with asthma or diabetes should generally get a shot (CDC, CDC).
  • Egg allergy is not a barrier. Babies under 6 months, people with a severe allergy to a vaccine ingredient other than egg, and people who had a severe reaction to a past flu vaccine should not get that vaccine; talk with your provider (CDC).

When

September or October is ideal for most people, by the end of October if possible; protection takes about two weeks to build. Most adults, especially those 65 and older, should avoid July and August because protection may fade. Some children need two doses at least four weeks apart and should start early (CDC). Later is still worthwhile: vaccination continues all season while flu is circulating (CDC).

What’s new for 2026–2027

  • CDC says that, “because of legal uncertainties and inquiries,” the recommendations from the July 2025 immunization schedule remain in effect for this season (CDC). We will update this page if that changes.
  • All three vaccine strains were updated, including protection against the A(H3N2) “subclade K” virus that spread widely in 2025–2026. The projected supply is all trivalent (three-strain), and 99% is free of the preservative thimerosal (CDC).
  • FDA has approved FluMist nasal spray for self-administration by adults aged 18 through 49, or by an adult caregiver for children aged 2 through 17, through an ordering program (CDC).

Why

Vaccination can reduce flu illness, doctor visits and missed work and school, and make illness less severe in people who still get sick (CDC). In people with heart disease it has been linked to fewer of some heart events, and flu shots have a long safety record in people with heart disease and diabetes (CDC, CDC). Effectiveness varies from season to season (CDC). If you have asthma, diabetes or heart disease, also ask about pneumococcal vaccines (CDC).

Another approach

Caring for someone with flu at home

CDC’s advice for caregivers (CDC):

  • Avoid being face to face with the sick person and keep close contact short. Hold a sick child with their chin on your shoulder so they don’t cough in your face.
  • Consider a mask, and wash your hands often — especially after touching the sick person or their tissues or laundry.
  • Clean and disinfect surfaces, and bring in fresh air or purify indoor air.
  • Call the doctor if the person gets very sick or is at higher risk; antivirals may help.

Encourage rest and plenty of water (NHS), check every medicine label for aspirin or salicylates in children and teens (CDC), and watch for the warning signs at the top of this page — especially symptoms that improve and then come back worse (CDC).

Member stories

Living with Flu (Influenza)? Share your experience

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Sources

This page is for education only and is not medical advice. Costs are typical U.S. ranges and estimates; yours will depend on your provider, location and insurance. Talk with your doctor before starting, stopping or combining any treatment. In an emergency, call 911. See our disclaimer.

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The Monterey Bay Holistic Alliance is a charitable, independent registered nonprofit 501(c)(3) organization and does not endorse any particular products or practices. Claims and statements herein are for informational purposes only and have not been evaluated by the Food and Drug Administration. We strongly recommend that you seek out your trusted medical doctor or practitioner for diagnosis and treatment of any existing health condition. MBHA provides administrative support, education and navigation — not medical, legal or tax advice — and cannot guarantee claim, billing or fundraising outcomes. MBHA is not an emergency service: in an emergency, call 911 or go to the nearest emergency room.