These Are the Most Effective Ways to Avoid Getting a Cold This Season

Higher blood levels of vitamin D are associated with fewer infections of the respiratory tract, according to one large observational study. Since vitamin D deficiency is so common, it's worth talking to your doctor about getting your levels checked. If you're deficient, your doctor can recommend an appropriate daily or weekly supplement. If you don't have a vitamin D deficiency, however, further supplementation to reach higher-than-normal blood levels isn't likely to be beneficial.

The benefits of probiotics may extend beyond gut health. More and more studies are finding a link between probiotics that contain lactobacilli and bifidobacterium and a decreased incidence of colds. Probiotic use is even associated with a decreased number of prescribed antibiotics for respiratory tract infections.

One small Japanese study found that adults randomly assigned to gargle water or povidone-iodine at least three times a day came down with significantly fewer respiratory infections than those who didn't gargle. Gargling was even associated with milder symptoms in those who did get sick. More evidence is needed before we can broadly recommend a gargling habit, but given that it's natural, harmless, and costs nothing, it may be worth a try.

Plenty of shut-eye seems to be at least partially protective against cold viruses. A 2015 study found that adults who reported getting less than five or six hours of sleep per night were four times more likely to develop a cold than those who reported getting seven hours or more.

Handwashing is the most consistently proven technique for preventing the spread of viruses, especially those associated with colds and the flu. To get the maximal benefit from this no-cost technique, make sure to wet both hands with water first, wash with soap for at least 20 seconds (you can even try singing the alphabet to make sure you're not cutting corners), dry hands completely, and turn the faucet off with a towel.

Increased immune functioning is among the many health benefits associated with regular exercise. Though rigorous clinical trials are lacking, a few small studies have suggested that consistent cardiovascular exercise is associated with a lower incidence of self-reported colds. And to set the record straight, exercising with a cold, when symptoms are predominantly "neck-up," is still recommended. If you have symptoms predominantly below the neck, like body aches or chest congestion, it's probably better to take it easy for a few days.

Though studies over the past few decades have yielded conflicting findings on the benefits of echincacea, a pooled analysis of these studies published in Lancet Infectious Disease found that, overall, echinacea appears to be associated with a small decrease in reported cold frequency, as well as a shorter duration of symptoms. But take note: the doses examined in the studies were high, typically around 300 mg three times a day, so it's unclear if the same benefits can be achieved at lower doses.

Though many healthcare workers and travelers, particularly in Asia, wear surgical-type face masks to prevent the acquisition of respiratory tract infections, a randomized controlled trial did not find this practice to be effective. In fact, subjects who wore masks reported more headaches than those who didn't. Bottom line: don't bother.

Studies in children have found that daily zinc sulfate, taken for at least five months, decreases cold frequency and school absences. Though there is probably a similar effect in adults who, like kids, happen to get colds frequently, keep in mind that zinc can lead to a decreased sense of smell, so it may not worth it if you only get colds occasionally.

Whenever possible, stay away from anyone who has cold or flu symptoms. People are typically most contagious about one day before symptoms develop until about five to seven days after the onset of illness. If complete avoidance is impractical, try to stay at least three feet away — that's the distance that virus-containing droplets from coughs and sneezes can travel.

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AT&T's chief medical officer, Dr. Geeta Nayyar, has warned that cell phones can "easily" spread the flu since they often come in close proximity to the face, especially the mouth. To decrease the risk, avoid sharing your phone, never use it in the restroom, and try a hands-free headset. You may also consider disinfecting it, though many cell phone manufacturers recommend against strong household cleaners including ammonia, alcohol, and other detergents.

A recent review of medical literature concluded that, in most people, vitamin C supplementation does not reduce the incidence of colds. But there was one group that did seem to benefit: those exposed to periods of severe physical exercise, especially in extreme conditions. Try a vitamin C supplement if you're training for a marathon, are an avid skier, or are frequently active in very low temperatures.

Not that you need it, but here's another reason to have sex more often: it may boost immune function. In a study among college students, those who reported having sex at least once or twice a week had a 30 percent increase in levels of salivary IgA, an antibody critical in the body's first line of defense against infections, compared to students who had sex less frequently. The response was even more pronounced in people who reported high levels of satisfaction in their relationships.

Most people don't realize how much they touch their face throughout the day, but studies estimate that the average person touches his or her face up to four times per hour. Catch yourself. The eyes, nose, and mouth are common entry sites for viruses, so keep your hands — especially when they're not washed — away.

Though washing hands with soap and water is the most effective way to prevent infections, a sink isn't always around when we need one. Try carrying a hand sanitizer, and make sure to choose one with at least 60 percent alcohol — less potent sanitizers won't eliminate germs as effectively. And don't waste your time with non-alcohol-based hand sanitizers: not only do they often fail to kill germs, but there is also evidence that they may cause microbes to develop resistance to the agent.

Rhinovirus — the usual culprit behind the "common cold" — can live on hard surfaces for up to 24 hours. If someone around you is sick, make sure to disinfect commonly used surfaces, like your workspace, kitchen counter, sink faucets, and doorknobs. But keep in mind that our environment is full of microbes, so unless you're using the same surfaces as someone with an infection, obsessive cleaning isn't necessary.

Though it seems like a given, the antismoking message is worth mentioning, since many people still smoke. Smoking damages the lining of the respiratory tract, from the nasal passages down to small airways in the lungs, which is why smokers tend to have more frequent and worse colds than those who don't smoke.

Though scientists haven't observed a direct link between meditation and the incidence of colds or the flu, there is emerging evidence that even short programs in mindfulness meditation may have a positive impact on the immune system. With so many other known benefits of meditation, there are few reasons not to try it.

Despite your best efforts to avoid the cold or flu this season, viral infections still get happen. If you do get sick, the CDC recommends staying home from work or school for at least 24 hours after your fever resolves to minimize the risk of transmitting the virus to others.