Herbs and Supplements for Cold, Flu, Cough and Sore Throat, Ranked by Evidence
The natural remedies with the best evidence for a cold are zinc lozenges started within 24 hours of the first symptom, which shortened colds by about a third in a meta-analysis of zinc acetate trials; Pelargonium sidoides extract (EPs 7630), which Cochrane found may speed recovery from acute bronchitis and colds; and andrographis, which relieved cough and sore throat faster than placebo across 33 trials. Elderberry has a mixed record: three small trials were strongly positive and the largest, most recent one was negative. Echinacea and vitamin C have the most trials and the smallest effects.
This guide is for otherwise healthy adults and older children with a viral cold, mild flu, chesty cough or sore throat who want to feel better faster. Nothing here prevents or treats influenza the way a vaccine or antiviral does, and the realistic benefit of the best options is a cold lasting 5 days instead of 7, or a cough that settles 2 days earlier. For cough, the best-supported remedy is not in our herb library at all: honey, which Cochrane found works at least as well as dextromethorphan in children over one year.
See a doctor rather than self-treating if you have breathlessness, chest pain, a fever above 39°C (102°F) or any fever lasting more than 3 days, a cough lasting more than 3 weeks, blood or rust-coloured sputum, a sore throat so severe you cannot swallow saliva, or symptoms that improved and then got worse. Babies under 3 months with a fever, anyone over 65, pregnant women, and people with asthma, COPD, diabetes, heart disease or a weakened immune system should call early, because flu antivirals only work in the first 48 hours.
Quick answer
- Zinc lozenges — 75–90 mg/day of zinc acetate started within 24 hours shortened colds by about 33% in a meta-analysis
- Pelargonium (EPs 7630) — Cochrane: may speed recovery from acute bronchitis and the common cold in adults and children
- Andrographis — faster relief of cough and sore throat than placebo across 33 RCTs with 7,175 patients
- Elderberry — symptoms resolved about 4 days earlier in a 60-person flu trial, but a 2020 trial of 87 patients found no benefit
- Echinacea — about 10–20% fewer colds with regular use in Cochrane's review; no clear effect once a cold starts
- Honey — Cochrane: relieves children's night cough at least as well as cough syrup (never under 1 year)
The 10 best herbs and supplements for cold and flu
Ranked by the strength of human evidence. Strong = multiple trials or a meta-analysis. Moderate = a few small trials. Preliminary = early or animal data.
Zinc lozenges
Strong evidenceHemilä's 2017 meta-analysis of 7 trials found zinc acetate lozenges delivering at least 75 mg of elemental zinc a day shortened colds by 33%, and the 2024 Cochrane review (34 trials) concluded zinc may shorten colds by about 2 days, with low certainty, while not preventing them. Form and timing decide everything: lozenges must be sucked slowly so zinc ions bathe the throat, started within 24 hours of the first symptom, and repeated every 2–3 hours while awake. Swallowed tablets and syrups showed no benefit.
- Key evidence
- Hemilä 2017 meta-analysis of zinc acetate lozenges (JRSM Open); Cochrane 2024 review
- Studied dose
- Zinc acetate or gluconate lozenge of 13–23 mg elemental zinc every 2–3 hours while awake (75–90 mg/day), starting within 24 hours, for no more than 7–10 days
- Best for
- Adults who can start at the very first tickle; not for prevention
- Cautions
- Nausea and metallic taste are common; avoid lozenges with citric acid or sorbitol, which bind zinc. Never use intranasal zinc, which caused permanent loss of smell (FDA warning 2009). Stop after 10 days, as high zinc depletes copper. Separate from quinolone and tetracycline antibiotics by 2 hours.
The 2013 Cochrane review of 8 trials found pelargonium extract may relieve acute bronchitis in adults and children and sinusitis and the common cold in adults, though the authors rated the evidence low quality because every trial came from one manufacturer and one country. In the largest bronchitis trial, 217 adults on EPs 7630 had a symptom-score drop of 7.2 points versus 4.3 on placebo after 7 days and returned to work 2 days sooner. It is a licensed medicine in Germany.
- Key evidence
- Timmer 2013 Cochrane review of 8 RCTs
- Studied dose
- 30 drops (1.5 mL) or one 20 mg tablet of EPs 7630 three times daily for 7 days, starting within 48 hours
- Best for
- Chesty cough and acute bronchitis; children over 1 year with a cold
- Cautions
- Rare liver-injury reports; stop for dark urine, pale stools or jaundice. Mild antiplatelet effect, so caution with warfarin. Not studied in pregnancy. Some liquid products contain alcohol.
A 2017 meta-analysis of 33 randomised trials with 7,175 patients found andrographis, alone or in the Kan Jang combination, relieved cough, sore throat and overall symptoms faster than placebo or usual care, with symptom scores roughly halved by day 3–5 in several trials. The evidence is graded low quality because many trials were small and poorly reported, but the direction is consistent. Trials used standardised extracts delivering 60 mg or more of andrographolides a day.
- Key evidence
- Hu 2017 systematic review and meta-analysis of 33 RCTs (PLoS One)
- Studied dose
- Standardised extract providing 60–90 mg andrographolides/day in 3 divided doses, for 5–7 days
- Best for
- Sore throat and the early, feverish stage of a cold
- Cautions
- Rash, headache and loss of appetite; rare severe allergic reactions. Lowers blood pressure and blood sugar and may inhibit platelets. Avoid in pregnancy (animal data suggest it may end pregnancy) and in autoimmune disease.
In a 2004 Norwegian trial, 60 people with lab-confirmed flu taking 15 mL of elderberry syrup four times daily recovered about 4 days faster than placebo, and a 2019 meta-analysis of 4 trials (180 people) found a large reduction in upper-respiratory symptoms. But the largest and most rigorous trial, Macknin 2020, gave 87 emergency-department flu patients elderberry extract or placebo and found no difference in symptom duration or severity. Honest summary: possibly helpful, probably overstated.
- Key evidence
- Hawkins 2019 meta-analysis of 4 RCTs; Macknin 2020 RCT (negative)
- Studied dose
- 15 mL standardised syrup four times daily, or 300 mg extract capsules 3–4 times daily, for 5 days from onset
- Best for
- Flu-like illness in the first 48 hours, alongside rest and fluids
- Cautions
- Only commercially prepared extracts: raw or unripe berries, leaves and bark contain cyanogenic glycosides and cause vomiting. Theoretically immune-stimulating, so avoid in autoimmune disease and with immunosuppressants. Not studied in pregnancy.
The 2014 Cochrane review of 24 trials and 4,631 participants found echinacea did not significantly shorten or ease colds once started, but prevention trials showed a small, consistent 10–20% reduction in the number of colds with regular use. Products vary enormously in species, plant part and extraction, which the reviewers blamed for the scatter. The best-studied product, Echinaforce (E. purpurea pressed juice), reduced recurrent colds and antibiotic use in a 4-month trial of 755 people.
- Key evidence
- Karsch-Völk 2014 Cochrane review of 24 RCTs
- Studied dose
- 2,400 mg/day E. purpurea pressed-juice extract for prevention over 4 months, or 4,000 mg/day for the first days of a cold
- Best for
- People who get several colds a winter and want fewer of them
- Cautions
- Allergic reactions, especially with ragweed, daisy or chrysanthemum allergy. Avoid with immunosuppressants and in autoimmune disease. Limit to 8 weeks continuous use; some regulators advise against it under 12.
The 2013 Cochrane review of 29 trials and 11,306 people is clear: regular vitamin C (200 mg or more a day) does not prevent colds in the general population but shortens them modestly, by 8% in adults and 14% in children, roughly half a day to a day. In people under heavy physical stress (marathon runners, skiers, soldiers) regular vitamin C halved the number of colds. Starting vitamin C after a cold begins, even at 1–3 g, had no consistent effect.
- Key evidence
- Hemilä & Chalker 2013 Cochrane review of 29 RCTs
- Studied dose
- 200–500 mg/day taken continuously through winter; large doses started once sick do not help
- Best for
- Endurance athletes, people doing hard physical work in the cold, children with frequent colds
- Cautions
- Above 1 g/day causes diarrhoea and raises kidney-stone risk, particularly in men. Avoid high doses in haemochromatosis and G6PD deficiency. Can interfere with some blood-glucose meters.
Ivy leaf extract is a licensed cough medicine across Europe. A 2016 placebo-controlled trial of 181 adults with acute bronchitis found the EA 575 extract reduced coughing fits and bronchitis severity scores more than placebo over 7 days, and a post-marketing study of 9,657 patients (5,181 children) reported improvement in 95% with few side effects. Its saponins loosen mucus and relax the airways. Combined with thyme, it cut coughing fits by 50% two days faster than placebo in a 361-person trial.
- Key evidence
- Schaefer 2016 RCT of EA 575 in 181 adults; Kemmerich 2006 thyme-ivy RCT of 361 adults
- Studied dose
- Dried ivy leaf extract 35–65 mg per dose (about 5 mL syrup) 2–3 times daily for 7 days; paediatric products dosed by age
- Best for
- Productive, chesty cough in adults and children over 2
- Cautions
- Nausea, diarrhoea and rare allergic skin reactions. Some syrups contain sugar or alcohol; check labels for children and diabetics. Not under 2 years without medical advice.
Thyme is approved by the German Commission E for bronchitis and cough, and two large German trials back it. Thyme-ivy syrup reduced coughing fits by 50% two days faster than placebo in 361 adults with acute bronchitis, and a thyme-primrose combination did the same in 361 more, with responder rates of 84% versus 55% on placebo at day 9. Thymol and carvacrol relax bronchial muscle and thin mucus; thyme alone has not been tested against placebo.
- Key evidence
- Kemmerich 2006 and 2007 RCTs of thyme combinations in 722 adults
- Studied dose
- Thyme-ivy or thyme-primrose syrup 5.4 mL three times daily for 7–11 days, or 1–2 g dried herb as tea 3 times daily
- Best for
- Productive cough with bronchitis, especially when ivy leaf alone is not enough
- Cautions
- Safe at tea and syrup doses. Thyme essential oil is not for swallowing. Avoid medicinal doses in pregnancy; theoretical bleeding risk with warfarin at high doses.
A 12-week trial of 146 volunteers taking an allicin-containing garlic supplement daily recorded 24 colds in the garlic group versus 65 on placebo, with shorter illness when colds did occur. Cochrane's 2014 review found this was the only trial meeting its standards and called for more research, so one good result stands alone. A 2012 trial of aged garlic extract in 120 people found fewer and milder cold and flu symptoms alongside changes in immune cell function.
- Key evidence
- Josling 2001 RCT of 146 volunteers; Lissiman 2014 Cochrane review
- Studied dose
- 180 mg allicin daily (one standardised capsule), or 2.56 g aged garlic extract daily, through winter for prevention
- Best for
- Prevention in people who get several colds a year
- Cautions
- Raises bleeding risk with warfarin, aspirin and clopidogrel; stop 1–2 weeks before surgery. Reduces levels of saquinavir and possibly other HIV drugs. Heartburn, body odour and bad breath at supplement doses.
Marshmallow root is a demulcent: its mucilage coats the throat and damps the cough reflex, which is why it has EU traditional-use approval for dry, irritating cough and sore throat. A 2018 observational study of 822 patients using marshmallow syrup or lozenges reported cough improvement within 10 minutes in most, but there is no placebo-controlled trial. Slippery elm and licorice work the same way with even less data, and licorice adds a blood-pressure problem.
- Key evidence
- Fink 2018 observational study of 822 patients; EMA traditional-use monograph
- Studied dose
- 1–2 g dried root as a cold-water infusion (steep 1–2 hours) up to 3 times daily, or 10 mL syrup as needed
- Best for
- Dry, tickly cough and raw sore throat; safe for children over 1 and in pregnancy at tea doses
- Cautions
- The mucilage can slow absorption of other medicines; take them 1–2 hours apart. May lower blood sugar slightly. No serious interactions known.
How to choose
- If you have just felt the first tickle (within 24 hours), the best-supported move is zinc acetate lozenges every 2–3 hours for up to a week. After day 2 the trial benefit disappears, so do not bother starting zinc on day 3.
- If the main problem is a chesty, productive cough, use ivy leaf or a thyme-ivy syrup, or pelargonium if you also feel wiped out with bronchitis. These are licensed cough medicines in Germany with real trial data.
- If the main problem is sore throat with fever, andrographis is the best-tested herb; marshmallow root or slippery elm lozenges soothe on the side. Honey in warm water does as much for the throat as any lozenge.
- If it is a dry, tickly night cough, honey is the best-evidenced remedy of all: 1–2 teaspoons at bedtime for anyone over one year. Never give honey to a baby under 12 months (infant botulism). Mullein, licorice and propolis are not ranked because none has a controlled trial for cough or cold.
- For prevention rather than treatment: regular echinacea (10–20% fewer colds), daily vitamin C if you train hard (halves colds in athletes), or garlic (one good trial). Vitamin C taken once sick does almost nothing.
- If it is flu, meaning sudden high fever, aches and exhaustion, elderberry is reasonable in the first 48 hours, though the newest trial was negative. If you are over 65, pregnant or have a chronic condition, call your doctor within 48 hours for an antiviral instead; ask AskMN if you are unsure which group you fall into.
What to skip
Oscillococcinum and other homeopathic flu remedies
Cochrane's 2015 review of 6 trials found no evidence of prevention and only a 7-hour reduction in symptom duration that could easily be bias. It is diluted until no molecule of the original duck-liver extract remains.
High-dose vitamin C once you are sick
Cochrane tested 1–8 g started at symptom onset and found no consistent effect. Vitamin C only shortens colds when taken daily beforehand, and only by about a day.
Intranasal zinc gels and sprays
They caused permanent loss of smell in more than 130 people and the FDA warned against them in 2009. Zinc only works as a lozenge dissolved slowly in the mouth.
Colloidal silver and 'immune-boosting' blends
Colloidal silver has no antiviral trials in people and causes argyria, a permanent blue-grey skin colour. Multi-ingredient immune blends usually contain token doses of a dozen herbs, none at the amount used in any trial.
Safety and when to see a clinician
- See a clinician for breathlessness, chest pain, fever above 39°C or lasting more than 3 days, a cough lasting more than 3 weeks, blood in sputum, a stiff neck with headache, or a sore throat you cannot swallow through. A cold that improves and then worsens may be a secondary bacterial infection.
- Call within 48 hours of flu-like symptoms if you are over 65, pregnant, or have asthma, COPD, diabetes, heart, kidney or immune disease. Antivirals only work early; herbs are not a substitute.
- Never give honey to a baby under 12 months (infant botulism). Do not give cough and cold medicines or herbal syrups to children under 2 without a doctor's advice; many contain alcohol, sugar or unstudied doses.
- Blood thinners: garlic, ginger, andrographis, pelargonium and high-dose thyme have antiplatelet effects. Immunosuppressants and autoimmune disease: avoid echinacea, elderberry and andrographis.
- Pregnancy: a few days of zinc lozenges, vitamin C, honey, marshmallow root tea and ginger tea are considered safe. Avoid andrographis, high-dose garlic supplements, licorice (raises blood pressure) and medicinal doses of thyme; pelargonium and elderberry are untested.
- Licorice root beyond 2 weeks or over 100 mg glycyrrhizin a day raises blood pressure and lowers potassium, a particular danger with diuretics, digoxin and heart disease.
What matters as much as any herb
- Sleep: people sleeping under 6 hours were four times more likely to catch a cold after viral exposure than those sleeping over 7 in a 2015 study. Rest is not optional.
- Fluids, steam and saline: warm fluids thin mucus and soothe the throat, steam eases congestion, and saline nasal rinses reduced symptom duration and viral shedding in trials.
- Hand hygiene prevents more colds than any supplement; viruses spread mainly from hands to nose and eyes.
- Flu vaccination reduces the risk of flu by 40–60% in a well-matched year and reduces severity when it does not prevent it. No herb comes close.
- Honey for cough: 1–2 teaspoons at bedtime for anyone over one year; Cochrane found it better than no treatment and at least as good as over-the-counter cough syrup.
Frequently asked questions
What is the fastest natural way to get rid of a cold?
Zinc acetate lozenges started within 24 hours of the first symptom and taken every 2–3 hours while awake shortened colds by about a third in the best trials. Nothing else acts as quickly. After that: pelargonium or andrographis for symptoms, honey for cough, and sleep.
How much zinc should I take for a cold and when?
Trials that worked used lozenges of 13–23 mg elemental zinc, sucked slowly every 2–3 hours while awake (75–90 mg a day), started within 24 hours of symptoms and continued for 7–10 days at most. Swallowed zinc tablets, syrups and lozenges containing citric acid did not work.
Does elderberry work for the flu?
Maybe. Three small trials found symptoms resolved around 4 days faster, but the largest and best-designed trial (87 emergency-department patients, 2020) found no benefit. Commercial extracts are safe and reasonable to try early, but they do not replace an antiviral in high-risk people.
What is the best herb for a cough?
For a chesty, productive cough, ivy leaf or a thyme-ivy syrup have the best trial data and are licensed medicines in Germany. For a dry, tickly cough, honey is better evidenced than any herb. Marshmallow root and slippery elm soothe the throat but have no controlled trials.
What is the best natural remedy for a sore throat?
Andrographis sped up sore-throat relief across many trials. For immediate comfort, honey and lemon in warm water, salt-water gargles and demulcent lozenges (marshmallow root, slippery elm) all help. A sore throat with fever, white patches and no cough may be strep and needs a swab, especially in children.
Does echinacea actually work?
Modestly, for prevention: taken daily it reduced the number of colds by about 10–20% in Cochrane's analysis. Taken once a cold has started, it did not significantly shorten or ease it. Products vary so much that one result cannot be assumed for another; E. purpurea pressed juice is the best studied.
When should I see a doctor for a cough or cold?
If a cough lasts more than 3 weeks, you cough up blood, you are breathless or have chest pain, fever goes above 39°C or lasts more than 3 days, or symptoms improve then worsen. Babies under 3 months with any fever, and anyone over 65 or with lung, heart, kidney or immune disease, should call within 48 hours of flu symptoms.
References
- Hemilä H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open (2017)
- Nault D, Machingo TA, Shipper AG, et al.. Zinc for prevention and treatment of the common cold. Cochrane Database of Systematic Reviews (2024)
- Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews (2013)
- Karsch-Völk M, Barrett B, Kiefer D, et al.. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews (2014)
- Timmer A, Günther J, Motschall E, et al.. Pelargonium sidoides extract for treating acute respiratory tract infections. Cochrane Database of Systematic Reviews (2013)
- Hu XY, Wu RH, Logue M, et al.. 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 (2017)
- Hawkins J, Baker C, Cherry L, Dunne E. Black elderberry (Sambucus nigra) supplementation effectively treats upper respiratory symptoms: a meta-analysis of randomized, controlled clinical trials. Complementary Therapies in Medicine (2019)
- Macknin M, Wolski K, Negrey J, Mace S. Elderberry extract outpatient influenza treatment for emergency room patients ages 5 and above: a randomized, double-blind, placebo-controlled trial. Journal of General Internal Medicine (2020)
- Kemmerich B, Eberhardt R, Stammer H. 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 (2006)
- Oduwole O, Udoh EE, Oyo-Ita A, Meremikwu MM. Honey for acute cough in children. Cochrane Database of Systematic Reviews (2018)
- Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database of Systematic Reviews (2014)
- Mathie RT, Frye J, Fisher P. Homeopathic Oscillococcinum for preventing and treating influenza and influenza-like illness. Cochrane Database of Systematic Reviews (2015)
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Ask about cold and fluThis guide is educational and is not medical advice. Herbs and supplements can interact with prescription medicines and are not regulated like drugs. Talk with a clinician or pharmacist before starting anything new, especially if you are pregnant, breastfeeding, have a chronic condition, or take medication.