Can you naturally boost your immune system before flu season?

Home Diagnostics

Vitamin C megadoses like those found in Emergen-C do nothing for a cold or flu and can increase your risk of kidney stones. Instead, get vaccinated and wash your hands often.

BestReviews is reader-supported and may earn an affiliate commission. Details.

Why you can’t “boost” your immune system

All year long, you can find supplements that claim to boost your immune system, but the ads are everywhere once the temperatures start to drop and flu season rolls around. It makes sense that you’d want to protect yourself from influenza, especially if you’ve ever had a serious case—it can be an extremely painful and psychologically draining illness. Plus, between 12,000 and 60,000 Americans have died from the flu every year for the past decade.

When it comes to products that claim to boost the immune system though, there’s one glaring problem: none of them actually do that. Peer-reviewed scientific studies have shown that the supplements, oils and other products touted as flu-prevention methods do very little or even nothing at all, and in rare cases can actually cause harm.

What is the immune system response?

First of all, what the immune system isn’t: it’s not a single response that either is or isn’t able to fight off an infection. From blood cells that recognize and destroy dangerous viruses to the coughing that removes phlegm from the body, it’s a vast network of activity that your body engages in when it senses that an invading pathogen is present.

Think about the last time you were sick. You may have had a fever, runny nose, chills, body aches or any number of other ailments. For the most part, these symptoms are not the virus attacking your body—these symptoms are, by and large, evidence that your immune system is actually working. As bad as your body aches and sneezing may have been, a “boosted” immune system would theoretically mean significantly worse body aches and sneezing, which is definitely not what you want. In fact, the best real-world example of an overly active immune system is an allergic reaction, something everyone wants to avoid.

“Immune-boosting” supplements and other snake oils

Throughout history, doctors, spiritual figures and everyday people have promoted various substances to prevent or alleviate illness. When you’re looking at whether a medicine is effective or not, it’s extremely important to maintain an evidence-based approach. The problem is, as normal people not trained in clinical study or the scientific method, a lot of us have a hard time parsing what scientific evidence actually means.

Here’s the gist of the drug development process, highly simplified. When researchers identify a plant, substance, molecule or method that shows potential in preventing or treating disease, that’s reason to study it further. If further study fails to show that the substance has any effect, science rarely if ever concludes, “This substance doesn’t work.” Instead, the wording is something along the lines of, “There’s no evidence to support that this substance has any effect.” That’s just how the scientific method works, and it works extremely effectively.

The problem is, to lay people like us, this leaves the impression that maybe said substance can still have an effect. However, you can rest assured that if there was any real reason to continue studying a chemical for influenza protection, that study would absolutely be conducted. Unfortunately, this doesn’t stop unscrupulous supplement manufacturers from pushing their unproven chemicals as effective illness prevention. For the perfect example of how pervasive this is, consider today’s most popular snake oil, which is virtually worthless: the vitamin C supplement.

Linus Pauling, vitamin C snake oil salesman

Scurvy is estimated to have killed some two million sailors between the years 1500 and 1800. In 1747, scientist James Lind discovered that oranges and lemons were remarkably effective at eliminating scurvy entirely. By the early 20th century, scientists learned of the specific compound in citrus fruits responsible for this powerful healing.

Over the next few decades, Linus Pauling became more and more obsessed with this citrus-borne, anti-scurvy treatment, now known as vitamin C. As the only person ever to win two Nobel Prizes individually, Pauling was certainly respected, both among the scientific community and society in general. In 1970, he published a book—not a peer-reviewed scientific study—touting the wonderful benefits of his now-favorite supplement. His publication was met with disdain by scientists around the world, but the damage was done. The general public saw this high-profile scientist’s obsession with vitamin C and began to buy into the claim that this one chemical could prevent or cure the common cold, along with other illnesses.

One fundamental problem with Pauling’s basic assertion is that the common cold isn’t a single illness, but rather a group of respiratory infections caused by various types of pathogens that change over time. Additionally, the methodology used in support of his claims was anything but scientific, fraught with poor logic, bad technique and multiple uncontrolled variables.

But Pauling didn’t stop there. He spent the rest of his life pushing the idea that massive doses of vitamin C, other vitamins and herbal supplements could eliminate the common cold forever, in addition to treating a large number of other, unrelated illnesses.

With significant public support for unproven supplements, science has spent decades researching them. After years of actual peer-reviewed research, not a single one of Pauling’s claims was proven correct. With regards to vitamin C, extensive metastudies of dozens of other papers determined that a cold patient who maintained the simple daily recommended dose of vitamin C could possibly reduce the duration of symptoms by 8 percent, or just a few hours in the case of most colds. Further study with a wide range of vitamins and supplements, like echinacea and turmeric, revealed similarly disappointing results in treating the common cold and many other ailments. By that point, scientists had definitively disproved that a megadose of vitamin C could cure anything.

To this day, unfortunately, the myth persists that a packet of powdered vitamin C can prevent or cure colds and influenza. Science-based medicine, however, hasn’t stopped moving forward, and there are definitive, medically-backed ways you can minimize your risk of getting sick.

How to really keep your immune system healthy

There aren’t any special supplements that boost your immune system, but there are lifestyle changes you can make to ensure that your body is in peak condition and able to fight off disease well. Regular exercise and eating healthy (including plenty of fruits and vegetables) plus generally maintaining a healthy body weight are some of the most important steps. A regular and sufficient sleep schedule can also make a huge difference.

An increasing amount of evidence also shows that smoking cigarettes or otherwise using tobacco can weaken your ability to fight off infections. Similarly, drinking excessive amounts of alcohol can lower your ability to stay healthy. Stress also negatively affects the body in multiple ways, not the least of which is making it easier to get sick.

How to keep from catching the flu

While science has firmly established that you can’t and don’t want to boost your immune system, there are things you can do to prevent getting sick. First and foremost is vaccination. The flu vaccine is never 100% effective because there are multiple strains of flu every year, but new vaccines are constantly being developed. Usually, the annual flu vaccine offers solid protection from three or four of the major variants active that year.

Killing flu germs

Purell Advanced

Of course, that’s not the only measure you can take. The influenza virus can live on surfaces and move between hosts, so washing your hands is a great first step toward protection. If you’re out and about, away from soap and water, a gel-based hand sanitizer like Purell Advanced makes a good substitute because it comes in 1oz bottles. If you want to supply an office or other shared space with extra security, a bulk container of hand sanitizer is another great choice. To use hand sanitizer, make sure to rub it in thoroughly for at least 20 seconds and don’t rinse it off.

Lysol Disinfectant Wipes

If you want to make sure that the actual surfaces around you are clean, Lysol is a good way to do so. Classic Lysol Spray is remarkably effective at killing germs, but keep in mind that it’s meant for use on surfaces and not for just spraying in the air. Lysol Disinfectant Wipes are also effective products to have on hand.

Preventing airborne influenza spread

these from Page One

There’s one simple and powerful piece of advice that you might be tired of hearing by now. If you want to reduce your risk of respiratory illness during flu season or otherwise, you might want to wear a mask. For the best possible protection, consider an N95 mask, as those are certified to remove airborne particles at a consistent rate. They’re not particularly stylish or comfortable, but if you’re willing to trade a bit of protection for comfort, cotton masks, like these from Page One, do offer a measure of protection and have a slot for a PM2.5 mask filter for increased effectiveness.

Treating flu symptoms

In the unfortunate case that you contract influenza, you’ll probably be okay in the long run, but you might have to deal with some unpleasant symptoms. The best advice from doctors is to rest, eat nutritious food, get plenty of sleep and drink lots of fluids.

If you’re experiencing significant muscle or joint pain during a cold or flu episode, you might be tempted to take some over-the-counter painkillers to feel better. While some people report success with NSAIDs like ibuprofen or naproxen sodium, there’s also a risk of these drugs exacerbating your symptoms and making you feel even worse. For this reason, many doctors recommend taking acetaminophen, the active ingredient in Tylenol. Make sure to consult with your doctor before using any such medications, even if they’re available over the counter. 

Finally, if at any point you feel really, really terrible when you have the flu, call your doctor or visit a health care professional. One rule of thumb is if you’re too dizzy to stand up or can’t keep fluids down, it’s probably time to go to the hospital.

While influenza is an unpleasant and potentially dangerous illness, with proper care you can greatly lower your risk and keep yourself and those around you safe.


Sign up here to receive the BestReviews weekly newsletter for useful advice on new products and noteworthy deals.

Chris Thomas writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

Copyright 2021 BestReviews, a Nexstar company. All rights reserved.