Cold and Flu Differences

I am a physician (an anesthesiologist) and I have continued to try to (silly me) find a really good description of the difference between Flu and Cold. This has really been nagging me, not only for my kids, but for me as well.
I did see the excellent article that you have on the site regarding not using antibiotics for colds. I couldn’t agree more! Do you feel antibiotics are overused for ear infections too, which after all may frequently be caused by colds?
Thank you.

Allan Zacher, MD

Cold and Flu Differences

Dr. Greene`s Answer:

I am so glad you asked this question. Cold and flu have become an inseparable pair, like salt and pepper or New Year’s and weight loss. Walking down the “cold and flu” aisle of any drugstore, you will find stacks of bright boxes with bold claims of help for those suffering from a cold or the flu. Since the two illnesses share some similar symptoms, and both come during “cold and flu season,” the two often run together in people’s minds. We have a vague idea that they are different, but if pressed, have a hard time saying exactly how. The significant distinctions between these two common conditions elude most of us, but the question is rarely raised.

The symptoms we get during a viral illness are often the body’s attempt to get rid of the virus and to minimize damage. Sneezing ejects the virus from the nose, cough from the lungs and throat, vomiting from the stomach, and diarrhea from the intestines. Fever makes it difficult for the virus to reproduce. The topic of viral illnesses will always remain somewhat confusing, since the body has a relatively small number of symptoms with which to respond to an ever-changing, wide variety of viruses. While colds and flus may overlap, the differences between them are important.

The common cold is centered in the nose.

Over 200 different types of viruses can cause a cold. Rhinoviruses, which means “nose viruses”, are the most common cause. Respiratory syncitial viruses (RSV) and a host of others can produce colds. Of note, influenza viruses occasionally cause illnesses with symptoms of the common cold.

The three most frequent symptoms of a cold are nasal stuffiness, sneezing, and runny nose. Throat irritation is often involved (but not with a red throat). Adults and older children with colds generally have minimal or no fever. Infants and toddlers often run a fever in the 100 to 102 degree range.

Depending on which virus is the culprit, the virus might also produce a headache, cough, postnasal drip, burning eyes, muscle aches, or a decreased appetite, but in a cold, the most prominent symptoms are in the nose. (By the way, forcing a child to eat with a decreased appetite due to a cold is both unnecessary and unhelpful, but do encourage drinking plenty).

If anything, using the term “common” with cold is an understatement. Colds are the most prevalent infectious disease. Children average 3 to 8 colds per year (younger children and boys are on the higher end of the range). Colds occur mostly in the winter (even in areas with mild winters). In areas where there is no winter, colds are most common in the rainy season. Parents get about half as many colds as their children do. Moms tend to get at least one more cold per year than dads.

When someone has a cold, the nasal secretions are teeming with cold viruses. Coughing, drooling, and talking are all unlikely ways to pass a cold. But sneezing, nose-blowing, and nose-wiping are the means by which the virus spreads. You can catch a cold by inhaling the virus if you are sitting close to a sneeze, or by touching your nose, eyes, or mouth after you have touched something contaminated by infected nasal secretions.

Once you have “caught” a cold, the symptoms begin in 1 to 5 days. Usually irritation in the nose or a scratchy feeling in the throat is the first sign, followed within hours by sneezing and a watery nasal discharge.

Within one to three days, the nasal secretions usually become thicker and perhaps yellow or green — this is a normal part of the common cold and not a reason for antibiotics. During this period, children’s eardrums are usually congested, and there may well be fluid behind the ears — whether or not the child will end up with a true bacterial infection. Yes, Dr. Zacher, antibiotics are too frequently prescribed for this as well.

The entire cold is usually over all by itself in about 7 days, with perhaps a few lingering symptoms (cough) for another week. If it lasts longer, consider another problem, such as a sinus infection or allergies.

While it lasts, the common cold is primarily a head cold. While you may feel tired or have aches, the illness is centered in the nose, and most of the symptoms are above the neck.

With the flu, you are sick all over.

The flu can be a much more serious illness. The most deadly recent worldwide outbreak was the flu epidemic at the beginning of this century and killed more than 20 million people. Even today, more than 36,000 people in the United States die from the flu each year — primarily those who are weak from advanced age or a major illness.

A single family of viruses — the influenza viruses — causes the flu. Most people get the flu once every year or two or three, and the illness is unpleasant but not usually dangerous. Unlike the common cold, both adults and children with the flu generally have a fever.

The flu can take many forms, but I will describe for you the most typical:

Classically, the flu begins abruptly, with a fever in the 102 to 106 degree range (with adults on the lower end of the spectrum), a flushed face, body aches, and marked lack of energy. Some people have other systemic symptoms such as dizziness or vomiting. The fever usually lasts for a day or two, but can last five days.

Somewhere between day 2 and day 4 of the illness, the “whole body” symptoms begin to subside, and respiratory symptoms begin to increase. The virus can settle anywhere in the respiratory tract, producing symptoms of a cold, croup, sore throat, bronchiolitis, ear infection, and/or pneumonia.

The most prominent of the respiratory symptoms is usually a dry, hacking cough. Most people also develop a sore (red) throat and a headache. Nasal discharge and sneezing are not uncommon. These symptoms (except the cough) usually disappear within 4 to 7 days. Sometimes there is a second wave of fever at this time. The cough and tiredness usually lasts for weeks after the rest of the illness is over.

Inhaling droplets from coughs or sneezes is the most common way to catch the flu. Symptoms appear 1 to 7 days later (usually 2-3 days). The flu is airborne and quite contagious, and with its short incubation period it often slams into a community all at once, creating a noticeable cluster of school and work absences. The flu usually arrives in the winter months. Within 2 or 3 weeks of its arrival, most of the classroom has had it.

The other major difference between the common cold and the flu is that the flu is preventable. In any given year, two or three different strains of influenza virus cause most of the flu around the world. Each year, scientists gather extensive global data and formulate a vaccine for the strains anticipated to be the major problems in the coming winter. While the prediction is usually accurate, sometimes new, unanticipated strains arise. In other words, in some years the vaccine works better than in others.

The CDC (Centers for Disease Control) currently highly recommends the flu vaccine for all children aged 6 months to 18 years, adults aged 50 years or older; persons aged 5–50 years with underlying chronic medical conditions; all women who will be pregnant during the influenza season; residents of nursing homes and long-term care facilities; children on chronic aspirin therapy; household contacts to any of the above groups; health-care workers involved in direct patient care; and out-of-home caregivers and household contacts of children aged <6 months. When supplies are sufficient, the CDC recommends vaccination of all persons who want to be vaccinated regardless of risk.

I prefer using versions of the flu vaccine without added thimerosal (a form of mercury) as a preservative. Most kids still get the flu vaccines with extra mercury. You might have to request ‘no added mercury’ to get the vaccine you want.

A nasal spray flu vaccine is now commercially available for nonpregnant, healthy people who are aged 5-49 years old. Over the next years it may become the more popular mode of flu vaccination due to its painless administration.

Of note, a new vaccine for pandemic H1N1 (initially referred to as the “swine flu” in the media) will be available in mid-late October 2009. This vaccine will be targeted towards the following high risk groups: pregnant women, household contacts or caregivers for infants less than 6 months, healthcare workers and emergency personnel, children and young adults 6 months – 24 years, and persons 25 years – 64 years with underlying medical problems. The number of doses recommended is similar to the seasonal influenza vaccine: a single dose for older children and adults, and two doses for children younger than 8-9 years of age (the exact age depends on the vaccine manufacturer). The pandemic H1N1 vaccine is expected to have a similar safety profile to the seasonal influenza vaccine.

For both seasonal influenza and pandemic H1N1, there is antiviral therapy available, such as Tamiflu or Relenza. However, antiviral agents – as well as hospitalization – are generally reserved for the very youngest, sickest, and highest risk patients.

Dr. Alan Greene

Dr. Greene is the founder of (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

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  1. riyaz

    I have a normal cold cough/alergy cough and fever 102 ‘bodyacah is there difference between in cold cough and H1n1 cough plz advised

  2. Sarah

    I have to say after my son and I had our flu shots in November, we still came down with the classic flu like symptoms in January despite the shot. We are on our 2nd week and the symptoms just seem to be evolving from one thing to the next.

  3. Jami

    After reading all this, I STILL don’t understand the difference even though this makes the most sense of everything I’ve read about the cold and flu.

    I recently had a very bad cold or flu. I feel like maybe it was a cold, because at first it was very centered around my nose – for about 4 or 5 days. But then it moved to my throat after about day 3 and lasted (very bad) for another 3 or 4 days. On top of that, a sinus infection must have ensued and my nose was very sore for another 4-5 days. And 3 weeks later I STILL have a sore throat, get really thirsty even though I am drinking plenty of fluids and am sleeping more than usual and I don’t understand why.

    I never had a fever because as soon as I started feeling achy and tired, I started taking Advil, which I pretty much kept taking every time I got a muscle ache. So maybe it was the flu?

    On day two, I couldn’t really do much — I laid in bed all day and had to postpone plans. On day three I felt slightly better, but by day 4 I was back in bed again. Dizzy and with the nose dripping and sneezing again.

    • Perhaps it was / is neither. With the soar throat and sinus infection, perhaps it was Strep or F-throat. If you’re still feeling miserable, you may want to see a doctor and get tested for a bacterial infection. Bacterial infections can be treated with antibiotics (though not always the best plan if your body can fight it off on its own). Viral infections can not be treated with antibiotics.

  4. Jennifer

    Hi there doctor. First, I am a 29 year old female and I have a couple questions, I have a few autoimmune disorders, such as psoriasis, crohns. I also take immune suppressors, such as humira and I just got off prednisone a month ago. I do take a multivitamins with immune support. This is really concerning me but I have had a cold/flu for 5 days now I have had a fever between 99-100.6, body aches, extreme fatigue, no appetite, nausea, vomiting and a cough. My boyfriend whom I live with got it first and still has a lingering cough. But what do you think this might be, cold or flu? And considering my illnesses, should I seek medical attention? I have had pneumonia before and my right lung is scarred. I’m just not quite sure on what I should do. Any advice I could get I would really appreciate it. Thank you.

  5. millie

    I got a cold and have been feeling tired all week and can’t stay awake in the day time. What should I do?

    • s oconnor

      Sleep gives your body the rest it needs, so don’t fight it. When you wonder why you are so’s because your body is fighting hard to make you well. There’s a war going on inside. All of your energy is thrust into the fight. So sleep. The cat naps will get shorter as your body wins the war..

  6. Anu

    Hi Doctor,
    My 22 months old daughter has cold( running nose) since from past 15 days. We gave cold syrup for first 5 days and stopped. Still continuing with nasal drops.

    I am bit worried. Do I need to consult doctor or it goes on its own. She die’t have cough or fever. So aim bit relaxed.

    Could you please suggest me on this.

    Kind regards,

  7. Payze Dues

    The CDC? The Center for Disease Creation? Vaccines? “Usually ACCURATE”? Tamiflu? Isnt that Donald Rumsfeld’s brand?Are you a joker? Discussion of vaccine production will turn most people’s stomach.Stop shilling for the establishment.

    • JD

      I think your tin foil hat might be on a little tight there, Payez. Get a grip, then join the rest of us out here in reality.

      • T

        I think you need to educate yourself JD, before you spew bullshit from your mouth.


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