How to Boost Immune System When Sick with a Cold or Flu

Disclosure: This article may contain affiliate links. If you decide to make a purchase, I may make a small commission at no extra cost to you.

When winter arrives, people start getting sick and they look for ways to boost their immune system by using supplements. Fortunately, nature does provide us with many powerful and proven natural ingredients, which can give your immune system a boost and prevent those nasty bugs from infecting you and making you feel miserable.

However, to get the most benefit from taking these supplements, first, you should make sure that you’re eating a healthy and balanced diet and you’re not deficient in any nutrients.

One of the reasons people often get sick is because their immune system is suppressed from eating a diet that is high in sugar and processed foods. Correcting vitamin and mineral deficiencies will normalize immune system function, and these supplements will then super-charge it.

Below are some of the top supplements available which can keep your immune system on high alert so that you don’t fall sick.

Top 5 supplements to boost your immune system

1. Garlic

Fast way to boost immune system using garlic

Garlic is a delicious ingredient that can be added to many different foods. Use it with your meals, so you can enjoy the health benefits that it offers.

Garlic not only helps boost the immune system, but its main active component called allicin is able to destroy pathogens like bacteria and viruses that can cause illness. Allicin supplements are also available for people who don’t enjoy eating raw or cooked garlic.

If you’re going to use garlic in your food, I recommend that you use a garlic crusher and then leave it to stand for a few minutes. After about 5 minutes, the allicin will have formed and you can consume it with some food or put it in a drink. This will quickly help relieve a sore throat or cold that may be developing. However, you must use this early, otherwise, it becomes less effective.

If you don’t fancy smelling of garlic by eating copious amounts of garlic every day, as I said, you can take garlic supplements. These have been proven to be effective in clinical trials at boosting a person’s immune system and protecting against the common cold. Just one allicin capsule is equivalent of 25 cloves of garlic! But without the smell.

Garlic has to be one of my favorite ingredients of all time. It’s always been highly effective in helping combat colds and stomach bugs that are going around, as long as it’s used during the early stages. When I’ve taken it too late, it’s only been mildly effective.

There are many studies published on the antimicrobial effects of garlic and allicin on PubMed. Most of the studies are in animal models, but there are now new studies being conducted on humans and some have shown remarkable effects.

If there was one food or supplement that I’d recommend you use often, it would be garlic!

Other benefits: Garlic lowers blood pressure, reduces AGE’s, lowers glucose, improves the gut by altering gut bacteria and therefore impacts the immune system in a positive way.


Ginseng is a fast way to boost immune systemGinseng has been touted to have many medicinal properties. It’s a treatment that has been used for many years for colds and flu, usually in countries such as South Korea and China. However, studies have found that North American Ginseng appears to be the most powerful in the treatment of acute respiratory infections.

One study found that this common herb can significantly shorten the length of colds by 6.2 days and it’s most effective when it’s taken for at least 2 months prior to an infectious challenge.

Ginseng also managed to reduce the number of colds by around 25% in five trials that examined the effects of the North American Ginseng (Panax quinquefolius).

Tips: Ginseng can be added to hot water to make ginseng tea or you can add it to smoothies. It’s also available in many different forms.

Other benefits: Helps boost metabolism to lose weight, as well as increase stamina, and lower blood sugar.


Green tea is a quick way to boost immune system

Green tea is one of my favorite drinks – I find it very comforting. There’s an old Chinese proverb which says: “rather three days without food than a day without tea”. I think drinking tea every morning after I wake up has become a ritual for me.

The reason why green tea is number three on this list is that it contains many polyphenols which are able to boost the immune system and kill pathogens.

Two of the main polyphenols in green tea that helps boost the immune system are EGCG and L-theanine. The most popular types of green tea include sencha and matcha.

Some studies suggest that EGCG directly inhibits entry and replication of viruses like the common cold, influenza, and others.

Tea also has been found to prime the immune system, so it can more quickly fight off infections before they have a chance to take hold.

Tips: Add some ginger and lemon to your tea to make even better. Citrus fruits may boost the benefits of drinking green tea and ginger contains gingerols which helps block inflammation. The ginger can also counteract any nausea that tannins induce.

Adding Manuka Honey to the tea is also a great idea if you have a bad throat and want to prevent bacterial throat infections. Gargling the tea might also be more effective in preventing throat infections.

Other benefits: Boosts metabolism for weight loss, protects against diabetes, high cholesterol, high blood pressure and more. In a study from Japan, researchers found that drinking 5 cups of green tea or more was able to reduce all-cause mortality for women by 23% and 12% for men.


Mushrooms can boost immune system fast

There are many different types of mushrooms, but Shiitake mushrooms have proven to be one of the most powerful in boosting immune function. Mushrooms contain beta-glucans which stimulate parts of the immune system, as well as decrease the level of inflammation in the body.

They help us to fight both viral and bacterial infections more effectively. Shiitake mushrooms are able to boost natural killer cells which destroy abnormal cells in the body, whether they are cancerous or have been infected by a virus

In a randomized study looking at human immunity and consumption of mushrooms, researchers noted significant and beneficial changes in the immune system after people consumed just five to ten grams of mushrooms daily.

However, if you don’t like eating mushrooms, I have good news! There are supplements such as AHCC available, which have been proven in clinical studies to help boost immunity. It contains a mix of alpha-glucans and beta-glucans, both of which have effects on the immune system.

Beta-glucans have been studied for years for their incredible ability to modulate the immune system in dramatic ways. To date, there have been over 6000 studies published in peer-reviewed journals which have looked at prophylaxis (prevention) and treatment of infectious disease using various types of mushrooms or beta-glucan supplements.

One study involving 162 people found that beta-glucan was able to reduce the number of colds by 25% compared to the control group.

I recommend that you keep a bottle of beta-glucan around in the winter to help boost your immune system!

Tips: Don’t continually take the supplement. I recommend that you take the supplement intermittently. There is the potential for the supplement to become less effective if taken over a long period of time.

Other benefits: May lower cholesterol, lower risk of cancer, and improve general well-being. Dietary mushrooms are also a good source of Vitamin D2.


Elderberry can be used to help support a healthy immune system and protect you from developing colds. Elderberries contain anthocyanins, which are strong antioxidants that block free radical damage from occurring in the body. Studies have shown that elderberries are also highly anti-inflammatory and have immunostimulatory effects.

In 2016, a study was published looking at the development of colds in air-travelers. The study was a randomized, double-blind, placebo-controlled clinical trial, and it confirmed previous findings that this fruit protects against colds and reduces cold symptoms.

The placebo group who never took the elderberry supplement had a much longer duration of symptoms compared to the treatment group (117 vs 57, p = 0.02). Symptom score was also significantly higher in the placebo group vs the treatment group (583 vs 247, p = 0.05).

Tips: Use elderberries in jams, sweets, pies, and other foods. Do not eat them raw! You can alternatively use elderberry gummies, which are safe to consume.


These are just some of the ways that you can quickly boost your immune system and protect yourself from developing infections. Natural products and foods contain compounds that are produced in nature to protect plants from all kinds of bacterial, fungal and viral infections that can do them harm.

We can benefit from taking some of these compounds, as they will help directly kill pathogens and even give our immune system a healthy boost!

Article reviewed and updated: March 2019.

You may also like


  • Hello, thanks for your great and longsighted blog, However, I have some doubts about green tea consumption, in particular when combined with calorie restriction. Both caffein and L-theanin act on the central nervous system, and regular consumption will create substance-related and psychological addictions; so although these substances are supposed to increase short term performance in cognitive tests, on the longer run the brain may forget how to work on its own without these substances, and actually get weaker.

    Also, Caffein, L-theanin and EGCG are all supposed to prevent diseases like Alzheimer’s or cancer. But then the question in my opinion is, how such diseases are created in the first place, and often one possible cause seems to be carbohydrate- or calorie-rich nutrition, the opposite of low-carb diets and calorie restricted diets. For example, a 2012 study on roundworms Caenorhabditis elegans says: “Both caffeine and bacterial deprivation extended life span when applied to worms independently, but did not produce an additive increase when combined at either 15°C and 20°C”. So caffeine did not help extend the life span, if the worms are already calorie restricted by depriving them of bacterial-rich food.

    Or for another example, looking at a recent news story, according to which a study “shows that in mice black tea alters energy metabolism in the liver by changing gut metabolites” Again, we should be skepitcal, since the mice in the experiment were always fed a “high-fat/high-sucrose diet”, the opposite of a calorie restricted diet.

    So my guess is, if calorie restricition is already implemented, regular green tea consumption may have no, or even detrimental effects.

    • Thank you for your comment Nikolaus. I think being skeptical about mice studies in general is a good idea when it comes to food and supplements. There’s more I have to say about this and will respond to your comment properly this weekend. 🙂 Cheers!

Leave a Reply

Your email address will not be published. Required fields are marked *