Index of Herbs

Concern guide

Herbs for Colds, Flu and Immunity

Herbs traditionally used through cold and flu season to soothe sore throats and coughs, what research shows, and when to see a doctor.

9 herbs reviewed

Updated October 10, 2026

Colds are common viral infections of the nose and throat that usually clear within a week or so. Flu (influenza) tends to arrive more abruptly, with fever, aches and exhaustion, and can sometimes lead to complications such as pneumonia. Almost everyone knows the feeling of being run down with a scratchy throat and a cough, and it is natural to look for gentle ways to feel more comfortable.

Herbs have a long history as cold-season companions. Several are traditionally used to support the body through a cold and to soothe sore throats and coughs, and a few have encouraging clinical trials. They work best alongside the basics: rest, fluids, ordinary pain and fever relievers where appropriate, and vaccination against flu and COVID-19. For people at higher risk of complications, or anyone who is very unwell, prescription antivirals started early can shorten flu by about a day and may help prevent complications, and a warm herbal tea or syrup can be a comforting addition to that care.

The list starts with the herbs that have the most promising research for colds, coughs and sore throats, then moves on to well-loved traditional remedies, ordered within each group by how commonly they are used. Product matters here: one species, plant part or combination may have trial data that another product sold under the same name does not, so each entry notes what was studied. Every herb links to its full monograph, and the safety section gathers the main precautions, especially for andrographis, goldenseal, licorice and echinacea.

02 The shortlist

The herbs, from best studied to time-honored

How to read the ratings

  • Good clinical evidence
  • Promising clinical evidence
  • Early or mixed evidence
  • Long traditional use

Ratings show how much research backs each herb for this particular concern. Every herb links to its full monograph, with preparations, safety notes, and sources.

  1. 01 Thyme

    Promising clinical evidence

    Thymus vulgaris

    Thyme is a favorite for a chesty, productive cough with a cold. Its best evidence comes from combinations: a thyme-ivy syrup and a thyme-primrose tablet each reduced coughing fits more than placebo in trials of 361 adults with acute bronchitis, and EMA accepts certain thyme–primula combinations as well-established for adults. Thyme on its own is a traditional remedy not yet tested against placebo. Avoid it with allergy to oregano or other mint-family plants.

    Read the thyme monograph →

  2. 02 Echinacea

    Promising clinical evidence

    Echinacea purpurea

    Echinacea is one of the best-known cold herbs, taken at the first signs of a cold. NCCIH says it may slightly reduce the chance of catching one, and EMA accepts the pressed juice of fresh E. purpurea as well-established for short-term prevention and treatment of colds from age 12, for up to ten days. Results vary between products, and whether it shortens a cold is still unclear. Avoid it with ragweed-family allergy, autoimmune disease or immunosuppressants.

    Read the echinacea monograph →

  3. 03 Andrographis

    Promising clinical evidence

    Andrographis paniculata

    Andrographis is an intensely bitter South Asian herb found in many cold and flu products, alone or in Kan Jang, a combination with a little eleuthero. A 2017 review of 33 trials found it eased cough and sore throat more than placebo and shortened symptoms, though most trials were of poor quality, and later COVID-19 trials found no benefit. The key caution is allergy: Australia linked it to 287 cases of anaphylaxis, including a death, and from September 2026 barred it from new low-risk medicines. Avoid it in pregnancy and breastfeeding.

    Read the andrographis monograph →

  4. 04 Elderberry

    Early or mixed evidence

    Sambucus nigra

    Elderberry syrups and extracts are a popular choice at the first sign of a cold or flu. Small trials of commercial berry extracts suggest shorter or milder symptoms when started within about 48 hours, but a 2020 placebo-controlled trial in 87 people with laboratory-confirmed influenza found no benefit, and a 2021 systematic review rated the evidence very uncertain and found it may not prevent illness. There is no reliable evidence for COVID-19. Choose products made from cooked ripe fruit, because raw or unripe berries, leaves and bark can cause serious stomach illness.

    Read the elderberry monograph →

  5. 05 Garlic

    Early or mixed evidence

    Allium sativum

    Garlic is a kitchen staple with a traditional EMA listing for relief of cold symptoms. In the one trial the 2014 Cochrane review could include, people taking garlic had fewer colds over three months, though colds lasted about as long, and the reviewers called for more research before recommending it. The cautions apply to supplements rather than cooking: added bleeding risk with anticoagulants, stopping seven days before surgery, and a contraindication with the HIV drug saquinavir.

    Read the garlic monograph →

  6. 06 Marshmallow Root

    Long traditional use

    Althaea officinalis

    Marshmallow root is a soothing mucilage herb that coats an irritated throat. EMA accepts it as a traditional remedy for throat irritation with dry cough from age 3, and doctors and parents rated it highly in studies of children, though those studies were uncontrolled. A blended tea with slippery elm and licorice eased sore-throat pain in a 60-person, manufacturer-led trial. Take it half an hour to an hour apart from other medicines.

    Read the marshmallow root monograph →

  7. 07 Licorice

    Long traditional use

    Glycyrrhiza glabra

    Licorice root is a classic ingredient in cough syrups and throat teas, valued as a soothing demulcent and mild expectorant. EMA lists it for productive cough on the strength of long use and pharmacology rather than large clinical trials. The key caution: with sustained use, glycyrrhizin can raise blood pressure and lower potassium, so limit glycyrrhizin-containing products to four weeks and avoid them with high blood pressure, heart or kidney disease, diuretics, digoxin or pregnancy.

    Read the licorice monograph →

  8. 08 Astragalus

    Long traditional use

    Astragalus mongholicus

    Astragalus is a Chinese tonic root with some 2,000 years of use, traditionally taken to help ward off colds. Small studies suggest it may enhance immune responses, but placebo-controlled trials measuring fewer infections are still lacking, and NCCIH says more reliable evidence is needed. Avoid it with autoimmune disease or transplant drugs such as tacrolimus.

    Read the astragalus monograph →

  9. 09 Goldenseal

    Long traditional use

    Hydrastis canadensis

    Goldenseal is a North American woodland root traditionally used for sore mouths and throats, and it is often paired with echinacea in cold remedies. Its alkaloid berberine is antimicrobial in laboratory tests, but NCCIH notes that no rigorous studies have tested goldenseal for colds or any other condition in people. Its main caution is drug interactions: it inhibits the CYP3A4 and CYP2D6 enzymes in people, which can raise levels of many prescription drugs, and it lowered levels of the diabetes drug metformin. Avoid it in pregnancy, breastfeeding and infancy.

    Read the goldenseal monograph →

03 Caution

Using these herbs safely

Most colds and many cases of flu can be cared for at home, and most of these herbs are well tolerated in short courses. A few symptoms are a sign to get medical care promptly instead. CDC lists emergency warning signs in adults that include difficulty breathing or shortness of breath, persistent chest pain or pressure, persistent dizziness or confusion, seizures, and fever or cough that improve and then return or worsen. In children, warning signs include fast or labored breathing, bluish lips, dehydration, fever above 104°F that does not come down with fever medicine, and any fever at all in a baby younger than 12 weeks. People at higher risk of complications, including adults 65 and older, young children, pregnant people and those with asthma, diabetes or heart disease, should contact a clinician early, because prescription flu antivirals work best when started within two days of symptoms.

A few herbs here act on the immune system or on how the body processes drugs, so they are worth checking with a pharmacist if you take regular medicines. EMA does not recommend echinacea for people with autoimmune disease, immune deficiencies or immunosuppression, and NCCIH advises people with autoimmune disease to avoid astragalus; both may work against transplant drugs such as tacrolimus and cyclosporine, and elderberry also deserves a clinician’s input in that setting. Echinacea is in the daisy family and can cause severe allergic reactions, including asthma and anaphylaxis, in people allergic to ragweed, chrysanthemums, marigolds or chamomile. Andrographis can cause sudden, severe allergic reactions, including anaphylaxis, usually within 30 minutes and often in people with no history of allergy; Australia’s medicines regulator recorded 287 cases, including a death, and in September 2026 removed it from the ingredients allowed in new low-risk medicines. Goldenseal inhibits the CYP3A4 and CYP2D6 enzymes that clear many prescription drugs, raising levels of the sedative midazolam by 40 to 60% in human studies, and it lowered levels of the diabetes drug metformin. Glycyrrhizin-containing licorice raises blood pressure and lowers potassium with sustained use and can be dangerous with diuretics, digoxin and corticosteroids; deglycyrrhizinated licorice (DGL) avoids most of this. Garlic supplements add to bleeding risk with anticoagulants and are contraindicated with saquinavir.

Pregnancy and breastfeeding: EMA does not recommend medicinal echinacea, thyme, marshmallow root or garlic preparations because safety has not been established, medicinal-dose elderberry is generally avoided, and andrographis, goldenseal and glycyrrhizin-containing licorice should not be used. Children: echinacea is not recommended under 12, and a pediatric trial found no benefit and more rash; EMA does not recommend elderberry fruit preparations under 18 or elderflower medicines under 12; marshmallow root is not recommended under 3; goldenseal must not be given to infants and has no established safety in older children. Never apply eucalyptus or thyme oil, or menthol rubs, on or near the face of a baby or young child, and never give essential oils by mouth.

Product quality varies, so it pays to read labels. Echinacea products differ by species, plant part and extraction, and US testing has found bottles that did not contain the labeled species. Elderberry products should be made from cooked ripe fruit; homemade preparations from raw or unripe berries, leaves or bark can cause poisoning, and testing has found some elderberry extracts partly or wholly replaced with cheaper black rice extract. Many cold remedies blend echinacea, andrographis, goldenseal, elderberry, zinc and vitamin C, which makes it hard to know which ingredient helped or caused a side effect; if you have ever reacted to a cold product, check labels for andrographis. Goldenseal is an at-risk woodland plant, so look for cultivated, documented root.

04 Questions

Frequently Asked Questions

For a chesty cough, the best-tested options are specific combinations of thyme with ivy or primrose, which reduced coughing fits in trials of adults with chest colds. Echinacea may slightly lower the chance of catching a cold, and elderberry has small trials suggesting shorter symptoms when started early, though the largest trial in confirmed influenza found no benefit. Andrographis has many trials suggesting modest relief of cough and sore throat, but most were of poor quality and it can cause anaphylaxis. For a sore throat, demulcent herbs such as marshmallow root can soothe for a short time. No herb reliably stops a cold, so rest and fluids still do much of the work.

Several herbs are traditionally used for this, and some, including echinacea and astragalus, change immune cell counts or cytokine levels in laboratory and small human studies. Those changes are interesting, but they are not the same as fewer or shorter infections, which is what research is still working out. Echinacea is best used as a short course: EMA’s approved course is at most ten days from the first signs of a cold, not all winter, and case reports of white-cell and autoimmune problems come from chronic daily use. That same immune activity is why people with autoimmune disease or on immunosuppressants are advised to avoid echinacea and astragalus.

Goldenseal is traditionally used for sore mouths and throats and is often paired with echinacea in cold formulas. Its alkaloid berberine kills microbes in test tubes, but NCCIH notes that no rigorous studies have tested goldenseal in people, and Memorial Sloan Kettering finds no evidence that it helps colds. Because it inhibits two major drug-metabolizing enzymes in people, it can raise levels of many prescription medicines and lowered levels of metformin in studies, so check with a pharmacist first if you take any. It should not be used in pregnancy, while breastfeeding, or in infants.

No. Elderberry and other herbs are best thought of as comfort measures alongside vaccination and, when needed, antivirals. They are not vaccines and have not been shown to prevent flu complications. CDC advises early antiviral treatment, ideally within two days of symptoms, for people at higher risk of complications or who are very sick, because antivirals can shorten illness and may help prevent complications such as pneumonia. Shortness of breath, chest pain, confusion, or any fever in a baby under 12 weeks needs medical care right away.

Echinacea is meant as a short course for adults and teens over 12, and a few groups should skip it or check with a clinician first. It belongs to the daisy family, and people allergic to ragweed, chrysanthemums, marigolds or chamomile can have severe reactions, including asthma and anaphylaxis. EMA does not recommend it for people with autoimmune diseases, immune deficiencies or immunosuppression, and autoimmune flares have been reported. Anyone taking transplant or other immunosuppressant drugs should talk with their care team before using it.

05 References

Sources

These references support the claims in this guide. Each herb’s monograph carries its own full source list.

  1. Colds, flu, and complementary health approaches: usefulness and safety

    National Center for Complementary and Integrative Health (NIH), 2016

    Federal overview of herbs for colds and flu, including echinacea’s possible small reduction in colds, its dependence on the product used, and a rash signal in children.

  2. Echinacea for preventing and treating the common cold

    Cochrane Database of Systematic Reviews (PubMed 24554461), 2014

    The 24-trial, 4,631-person review showing that echinacea products vary too much to pool, with a possible small preventive effect.

  3. Elderberry for prevention and treatment of viral respiratory illnesses: a systematic review

    BMC Complementary Medicine and Therapies, 2021

    Supports the conclusion that elderberry may not prevent illness and that evidence for shortening it is still too uncertain for firm conclusions.

  4. Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysis

    PLoS One (PubMed 28783743), 2017

    Supports the promising-evidence rating for andrographis: 33 randomized trials with 7,175 patients found improved cough and sore throat versus placebo and shorter symptoms and sick leave versus usual care, but overall trial quality was poor.

  5. High-moderate risk changes to permissible ingredients - Andrographis paniculata 2026

    Therapeutic Goods Administration (Australia), 2026

    Source for the anaphylaxis caution: andrographis removed from Australia’s low-risk listed medicines from 17 September 2026 after continued anaphylaxis reports, including a death reported in 2024.

  6. Efficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves and matched placebo in adults suffering from acute bronchitis with productive cough

    Arzneimittelforschung (PubMed 17063641), 2006

    The 361-adult placebo-controlled trial of a thyme-ivy syrup that underpins thyme’s rating for cough with a cold.

  7. In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes

    Clinical Pharmacology & Therapeutics, 2005

    Human study showing goldenseal inhibits CYP3A and CYP2D6, the basis for this page’s drug-interaction caution.

  8. Signs and Symptoms of Flu

    Centers for Disease Control and Prevention, 2024

    Source for the emergency warning signs of flu in adults and children, including any fever in babies under 12 weeks, and for higher-risk groups.

  9. Treatment of Flu

    Centers for Disease Control and Prevention, 2025

    Supports the advice that prescription antivirals work best within two days of symptoms, shorten illness by about a day, and matter most for higher-risk patients.

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