Preventing Colds, Flus & Infections

Whatever shape your immune system is in, it makes sense to minimize the overwhelming numbers of disease-causing germs you are exposed to in order to minimize colds, flus, and infections.

Dr. Greene’s Answer:

As an active pediatrician, I am exposed to every cold and flu virus in every daycare center in our community. Think about it! Sneezed on, slobbered on – I even wind up examining poopy diapers that parents bring in for my educated opinion. I have a front row seat to contagious diseases.

I am often asked how I manage to avoid so many of the colds, flus, and diarrheal illnesses that sweep through town. Part of the answer is that, over the years, my immune system has met many of these microscopic invaders, learned about them, and now stands ready with antibodies to prevent infection. This has happened over time, often with no conscious help from me. Appropriate vaccines do this same job in a number of instances (I get the flu vaccine each year, for instance).

When possible, I try to help keep my immune system functioning in peak form. Getting good nutrition (plenty of fresh fruits, vegetables, and supplements for the areas in which my diet is not adequate) is a foundation for good health. Plenty of good sleep is vital (perhaps the toughest one for me). Plenty of activity (a brisk walk by the waterfront is my favorite), and lots of love and laughter both strengthen the immune system (read the compelling Anatomy of an Illness by Greene family friend Norman Cousins if you’ve missed this classic). Avoiding inordinate stress helps too – and this is something I’ve still got a lot to learn about.

Whatever shape your immune system is in, it makes sense to minimize the overwhelming numbers of disease-causing germs you are exposed to. There are four key ways to do this.

Decrease the Disease-causing Germs on Surfaces in the Home

Where are these germs truly a problem? Where does this really make a difference? In a number of different fascinating studies, researchers have carefully cultured every imaginable surface of typical homes to find where the disease-causing germs live. It turns out that the kitchen harbors more germs than any other room in the home — yes, more than the bathroom. The greatest concentration is found in the moist germ havens we call kitchen sponges and dishcloths. These are the very same germs with which people in that household get sick. Sink drains, faucet handles, and doorknobs — either in the kitchen or bathroom — are the next highest on the list. Toilet seats had fewer germs than any other surface tested (Journal of Applied Microbiology, 1998;85(5):19–28)! If we can keep these objects clean — especially the sponges and dishcloths — we can cut the spread of infection.

But here’s the problem:

Tossing a dishcloth in the washing machine, even with a strong detergent, doesn’t appreciably cut down on surviving germs. The micro-crevices that make a sponge such an effective cleaning device make it even more difficult to disinfect. Running a sponge through the dishwasher makes it look clean but leaves it just as infectious. Even strong chemical disinfectants often aren’t enough to disinfect them (Journal of Applied Bacteriology, 1990;68(3):279–283).

Wet your sponge or dishcloth and then pop it in the microwave for 2 minutes. Then you’ll have safe, germ-free tools to use. For items that you can’t microwave, such as faucet handles, a household cleaning solution containing hypochlorite is the best for cleaning, but be sure to rinse thoroughly (Journal of Applied Microbiology, 1998;85(5):819–828).

Decrease Disease-causing Germs in the Air we Breathe

I use every opportunity to teach children (and adults) to cover the mouth and nose for every cough and sneeze. This simple maneuver has spectacular results in decreasing the aerosolized viruses and bacteria floating about the room for us to inhale. Of course, this does leave the hands or tissues teeming with germs, but we’ll deal with that in a moment.

To keep the air clean, I also rely on special air filters. These high-efficiency particulate-arresting (HEPA) filters, available at discount drug stores for about $40 to $100, can remove 99.97%+ of the pollen, dust, animal dander, and even bacteria from the air. They are especially effective at preventing infections for those that get a bit stuffy from allergies but can also decrease respiratory infections for everyone. I have several in my pediatric office (you know what waiting rooms are like!) and several in my home, so that the room air is completely filtered six times an hour. Houseplants are also excellent air purifiers (if no one is allergic), although they work much more slowly.

Avoid Antibiotic Soaps (except for medical scrubbing)

At this year’s science fair at my children’s school, young students performed an elegant experiment using antibiotic soaps. They put a few drops of the soap in one test tube, a few drops diluted 10x in water in the next, a few drops diluted 100x in water in the next, and a few drops diluted 1000x in water in the final tube.

They took normal bacteria from classmates’ hands and placed a sample in each tube. All hand bacteria were killed in the first three tubes, but a few survived in the most dilute tube.

They kept these survivors, grew them in an incubator, and repeated the experiment using these hardy bacteria. This time they were able to survive in two of the test tubes. By continuing this process, they were able to breed increasingly resistant bacteria.

The children reasoned that whenever we wash our hands, some areas around the edges get only dilute concentrations of soap. This is the ideal breeding ground for the bacteria we want to avoid. They proved that, as is the case with oral antibiotics, antibiotic soap can produce increasingly troublesome bacteria.

In most cases, antibiotic soap gives no added benefit, and may even increase your chances of getting sick. Note: disinfectants (on surfaces) and antiseptics (on people) mechanically destroy germs. They are different than antibiotics and are useful in preventing infections.

Wash Hands at Many Important Times Throughout the Day

Most common infections are “caught” when the germs get on our hands and then we touch our eyes, noses, or mouths. Proper hand washing is an enormously effective method of prevention. I wash my hands before and after seeing each patient in my office. I recently underwent neck surgery. I’m more pleased that my neurosurgeon scrubbed his hands thoroughly than that he wore sterile gloves. Hand washing is more important.

Even in 1999, lack of proper hand washing remains the number one source of infections acquired in hospitals (Annals of Internal Medicine, 1999;130(2):126–130)! Practicing what we already know could prevent unnecessary suffering and misery.

The same is true for children. In a recent study of 341 children’s daycare centers, infrequent washing of children’s or providers’ hands after nose wiping, after diapering, before meals, and before food preparation was spectacularly associated with a higher frequency of illness. Use of shared cloth towels instead of individual paper towels and washing of sleeping mats less than once a week were also associated with a higher frequency of illness. Hand washing and other hygiene practices actually do reduce the spread of disease (Public Health, 1998;113(6):544–551).

The most important times for most of us to wash our hands are after sneezing or coughing, after toileting, upon leaving “high-risk” places (pediatrician’s waiting rooms, ball pits, daycare centers, fast-food chain play structures, high-traffic door knobs, etc.), and always upon arriving home (to keep outside germs outside). Of course, hand washing before meals and snacks is a must. (Before a child picks his or her nose would be nice but is not always practical.)

Lots of water and a moisturizing soap are a great way to wash, but this isn’t easily available at all the right moments. I’ve found a recent innovation to be portable, practical, and fantastic. Instant Hand Sanitizers, are a wonder. Talk about convenient! A small bottle can be carried about in a purse, glove compartment, or even a hip pocket. A little dab will kill 99.99% of germs without any water or towels. It uses alcohols to destroy germs physically. It is an antiseptic, not an antibiotic, so resistance can’t develop. They’ve added moisturizers and vitamin E to counteract the drying tendency of the alcohols. A few people find it irritating to the skin, but most find it refreshing to use and that their hands feel smooth and soft afterward. You may want to use an additional moisturizer.

And here’s the cool part — it’s fun. Many kids think it’s a treat to get to use it! It’s finally actually possible for busy parents (and grandparents and daycare providers) to get those hands washed all those times you wish you could. We asked my son’s preschool to start using it and they agreed. The kids took to it quickly and we are all happy.

These four keys are my secrets. I hope they help you and your family.


Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.

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