Two years ago, I acquired a case of flu and was sicker than I had been in a long, long time. Some time after healing, I found recommendation for four herbs to be used in an effort to prevent getting the flu: Astragalus Root, Eleuthero Root, Asian Ginseng Root, and Licorice Root. \n\nAstragalus Root (Astragalus membranaceus) is a highly beneficial herb. According to Donald Yance in Adaptogens in Medical Herbalism, Astragalus . . . "improves and balances the immune system and boosts the vital force, providing the immune system with the energy needed to perform. It is most important for people with weakened immune systems, such as the elderly or people with cancer." It is also specific to the immune system as it resides in the lungs.\nAccording to Traditional Chinese Medicine, Astragalus Root should not be used when sick, only as a preventive.\nCautions: If using immune-suppressing drugs, Astragalus Root is contraindicated. Also, Astragalus Root may make it hard for the body to get rid of Lithium, so levels of Lithium may build to a dangerous level.\nEleuthero Root (Eleutherococcus senticosus) is another very beneficial herb. Once again, Donald Yance, in Adaptogens in Medical Herbalism, states that research has "demonstrated that Eleuthero Root prevented and treated infectious diseases such as the flu." In other words, this herb may be used to prevent as well as treat the flu.\nCautions: It's possible that Eleuthero Root may interact with the cardiac medication digoxin.\nAsian Ginseng Root (Panax ginseng) is a well-known and extremely beneficial herb. It is thought to be the most stimulating of the adaptogenic herbs which makes it applicable for use in weak, exhausted people. It can assist the immune system in returning to normal function. Known as the lord of herbs, it supports the kidneys, liver, lungs, spleen, and heart.\nCautions: Type A personalities should avoid large quantities of Asian Ginseng Root or at the very least, avoid drinking coffee if using the herb.\nLicorice Root (Glycyrrhiza glabra), the fourth and last of the herbs I choose to use for immune function, supports immune activity when used in the whole root form. It helps to restore vitality. It also helps to remove heat, moisten the lungs, and stop coughing.\nCaution: If you're prone to high blood pressure, this herb is contraindicated.\nThe following information has been excerpted from Donald Yance's book Adaptogens in Medical Herbalism:\nRegarding Astragalus Root:\n"There are no known side effects or toxicity from taking Astragalus Root. It is considered one of the safest herbs to use and is well suited for all people - young, old, weak, strong, and even small children and infants (dosage would need to be adjusted accordingly)."\nRegarding Eleuthero Root:\n"Eleuthero Root is well tolerated and free of side effects and can be taken for long periods of time. Eleuthero Root extract was recently found not to disrupt drug metabolism pathways, demonstrating its safety even when coadministered with drugs. A recent rat study found no negative interaction between Eleuthero Root and warfarin."\nRegarding Asian Ginseng Root:\n"If taken as a single herb, particularly by those who are type A and prone to anxiety, Panax ginseng is too stimulating and not indicated. Panax (red ginseng) should only be used by very deficient, pale, weak persons. The side effects greatly depend on the form and strength of the Ginseng used and the person's constitution. I never use Ginseng Root alone; it is always combined with other adaptogens and supportive herbs. Therefore, I do not find this herb to cause the side effects that may occur if it were taken as a single herb. In general, I have found that many herbs combined together synergize, supporting one another, and can offset the side effects that may be attributed to a single herb."\nRegarding Licorice Root:\n"Caution is advised for people who may have hypertension and are prone to fluid retention. Licorice Root, at high doses, because of its effects on aldosterone, can exacerbate or induce fluid retention, raising blood pressure. The mechanism of this side effect, pseudoaldosteronism, is due to Licorice Root's inhibition of 11beta-hydroxysteroid dehydrogenase. The excess of endogenous cortisol produced in such situations combines with the renal mineral corticoid receptor, which promotes an aldosterone-like action. There is a dose-response and a time-response relationship between Licorice Root consumption and a rise in blood pressure.\n"In other words, people who are salt-sensitive and who retain fluid when consuming too much salt can be prone to water retention and thus hypertensive to the effects of high-dose Licorice Root. These persons should avoid Licorice Root; however, in the typically low percentages in which it is included in most formulations there is no need to be concerned. Otherwise, people who are hypotensive and dehydrated from a poor ability to absorb water often get great benefit from Licorice Root and from eating foods naturally rich in salt, such as miso, seaweed, feta cheese, and olives. \n"Licorice Root is traditionally used in formulations involving other herbs, not as a single herb. Taken within the recommended therapeutic dosage range, it is very safe."\nI use these four herbs at the same time, each in liquid extract form, taking in much smaller amounts of the Asian Ginseng and Licorice Root than of the Astragalus Root and Eleuthero Root. I have been dosing with these four extracts every day for over two years.\nBecause of the pandemic, I also like to make a cup of tea using Ginger Root powder, Cinnamon Bark powder, Turmeric powder (1\/2 tsp of each) and Cayenne powder to taste. The sweetener I use is Maple Syrup, but honey may be used instead. Piping hot, this tea is wonderful for the lungs.\nSources: Donald Yance's Adaptogens in Medical Herbalism; David Winston's Adaptogens, Herbs for Strength, Stamina, and Stress Relief.