Two small flu trials, one industry-funded cold study and a meta-analysis of 180 people built a reputation almost nobody questions. The one adequately powered trial found no benefit. This is a supplement my readers like, so it gets the same standard I would apply to a drug.
Every October the elderberry syrup appears — in the health food shop, beside the vitamin C in the supermarket, in the group chat where someone posts the recipe with the cinnamon stick and the raw honey. It is one of the few supplements almost nobody argues about. People who will not touch a multivitamin keep a bottle for the children.
I like elderberry, and that is exactly why it belongs here. The question of who decides what goes in the bottle has to be asked hardest about the things we are already inclined to believe. When I wrote about the shingles vaccine I held it to trial evidence, funding and effect size. Elderberry gets the same treatment, graded the same way: strong trial evidence, mixed, mechanistic and untested, or none.
Sambucus nigra, the European black elder. The berries are dark purple-black and owe their colour to anthocyanins, the group of phenolic compounds usually credited with whatever activity the extract has. Commercial products are syrups, lozenges, gummies and capsules made from processed berry extract, and they are overwhelmingly sold for colds and flu.
Elderberry extract shows activity against influenza strains in the laboratory, and the early clinical papers open with that work. That is a reason to run a trial. It is not a reason to expect one to succeed — a great many compounds that stop a virus in a dish do nothing measurable once swallowed by a person who already has the infection.
So the question is not whether elderberry does something to a virus in a laboratory. It is whether a person who takes it gets better faster. Only trials answer that.
If you have read anything about elderberry you have met the claim that it shortens flu by around four days. The figure is real and published, and it comes from two small studies.
The first was run during an influenza B outbreak on an Israeli kibbutz and published in 1995, using the Sambucol product. The second was a Norwegian trial published in 2004: sixty patients with flu-like symptoms of less than 48 hours, given elderberry syrup or placebo four times a day for five days. Symptoms were relieved on average about four days earlier with elderberry. The paper’s own conclusion says the result needs confirming in a larger study.
Sixty people, one flu season, symptom scores recorded by the patients. That is the foundation the syrup bottle is trading on. It is not fraud and it is not nothing. It is a small positive signal that went sixteen years without a properly sized test.
The test arrived in January 2018 at the Cleveland Clinic. It ran to April 2019 across three emergency rooms, it was investigator-initiated, and it was conducted under an FDA Investigational New Drug application — a higher regulatory bar than any elderberry trial before it had cleared.
Eighty-seven patients aged five and over, all with PCR-confirmed influenza and less than 48 hours of symptoms. Children aged five to twelve took 15 ml of elderberry extract twice a day; everyone older took it four times a day, for five days. Patients could also choose to take oseltamivir. This is the trial you will see described as the paediatric one. It was not a paediatric trial: children were included, but the average age was 25.
There was no benefit. Placebo reached none-or-mild symptoms in 4.9 days; elderberry took 5.3. Complete resolution took 8.7 days on placebo and 8.6 on elderberry. Neither difference came close to significance.
Two details matter more than the headline. The trial was powered above 0.90 to detect a two-day benefit — so if elderberry did half of what the Norwegian study reported, this trial would almost certainly have seen it. And in a post-hoc look at patients who took elderberry without oseltamivir, the primary outcome came out about two days worse than placebo alone. A post-hoc finding in a trial of 87 people is a question, not an answer, and I am not telling you elderberry prolongs flu. But it points the opposite way from the label, and it came out of the most rigorous trial there is.
The other study you will see quoted is the 2016 air travel trial: 312 economy passengers flying long-haul out of Australia, taking elderberry capsules from ten days before travel until four or five days after arrival. It is the largest elderberry trial, and its conclusion — shorter, milder colds — is the one the marketing uses. Read properly, it says something narrower.
It did not prevent colds. Seventeen cold episodes on placebo, twelve on elderberry, and the difference was not significant. Only 29 of the 312 participants caught a cold at all, so every number in the headline rests on those 29 people. The significant result was a pooled count of cold days — 117 on placebo against 57 — analysed as cumulated events, which treats one person’s six sick days as six independent observations and tends to make a result look stronger than it is.
The paper also disagrees with itself. Its abstract gives the cold-day difference as p = 0.02 and the symptom score as p = 0.05; its results section gives those two figures the other way round. One is transposed. I could find no correction on PubMed or PubMed Central.
None of that makes it worthless. It suggests that among people who catch a cold anyway, elderberry may shorten it. That is a much smaller claim than “supports immunity through the winter”, and it is the honest one.
A 2019 meta-analysis is often cited as the clincher, reporting a large effect on upper respiratory symptoms. It pooled 180 participants in total — one modest trial’s worth of people. Its four authors were at a private wellness institute rather than a university or hospital research unit. And it was published before the Cleveland Clinic trial, so the one adequately powered negative trial is not in it. Every citation of it since 2020 is quoting a summary of the evidence that leaves out the best study.
The air travel trial says it plainly, to its credit: it was funded by Iprona AG, the Italian company whose extract was tested. The sponsor supplied the elderberry and placebo capsules and was partly involved in designing the study; randomisation, data collection, analysis and publication stayed with the university team. That is how most supplement trials are paid for, because nobody else pays for them. But a trial funded, supplied and partly designed by the manufacturer belongs in a different tier from an independent one.
The Cleveland Clinic trial gets the same scrutiny. Its conflict-of-interest declaration records two things: that the lead investigator has been vegan for ten years and that the Wendel Family Foundation is supportive of plant-based nutrition; and that he explored patenting a combination of oseltamivir and elderberry extract, which the Clinic’s innovations department judged not patentable. Both of those interests point towards elderberry doing something, not against it. The investigator most likely to have wanted a positive result reported that there wasn’t one.
Norway, 2004: elderberry syrup, 15 ml four times a day for five days, started within 48 hours of symptoms.
Cleveland Clinic, 2018–19: 15 ml (5.7 g) of extract twice a day for children aged 5–12 and four times a day over 12, for five days. No benefit at either dose.
Children generally: there is no established paediatric dose. Most of the research was done in adults, and the one trial that included children found no benefit. The gummies marketed to children are sold on an evidence base that did not include them.
Here the honest answer is that it doesn’t. No test identifies someone who needs elderberry, and elderberry corrects no measurable deficit. It is a symptomatic remedy taken after an infection has started, which puts it outside the thing this site is built around: finding what is actually wrong and addressing that.
What testing can do is address the things that decide how a winter goes — vitamin D status at this latitude, iron and ferritin, protein intake, sleep and the stress load that drives cortisol. Those have better evidence behind them than anything in the elderberry literature, and the risk of a supplement with a good story is that it takes their place.
If a drug company brought me two small trials and a meta-analysis of 180 people, followed by one properly powered trial that found nothing and a post-hoc signal pointing the wrong way, I would say the drug does not work and the early studies were noise. The only honest thing to do with elderberry is say the same.
Raw and unripe elderberries contain cyanogenic glycosides, as do the leaves, bark and stems. The berries are safe once properly cooked, and commercial extracts have a good safety record across the trials. If you are making syrup at home, the berries must be ripe and simmered properly, and the green ones and the stalks do not go in. That is the step not to skip, and October is when people skip it.
Graded, then. Prevents colds or flu: no evidence — the largest trial looked and did not find it. Shortens flu: mixed, and the best-designed trial says no. Shortens a cold once you have one: weak and industry-funded, from 29 people. Safety: good for processed products in adults at trial doses; real for raw or unripe berries; no established dose in children.
So I do not tell people to throw the syrup out. It is cheap, pleasant and low-risk when properly made, and if you take it in November and feel better, the world has bigger problems. What I will not do is let it take the place in someone’s winter that sleep, protein, vitamin D and not being run into the ground actually deserve. Liking the answer is not evidence — that holds for a berry exactly as it holds for a drug.
Study records retrieved from PubMed and PubMed Central.
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. J Gen Intern Med 2020;35(11):3271–3277. doi:10.1007/s11606-020-06170-w · ClinicalTrials.gov NCT03410862
Tiralongo E, Wee SS, Lea RA. Elderberry supplementation reduces cold duration and symptoms in air-travellers: a randomized, double-blind placebo-controlled clinical trial. Nutrients 2016;8(4):182. doi:10.3390/nu8040182
Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Int Med Res 2004;32(2):132–140. doi:10.1177/147323000403200205
Zakay-Rones Z, Varsano N, Zlotnik M, et al. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama. J Altern Complement Med 1995;1(4):361–369. doi:10.1089/acm.1995.1.361
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. Complement Ther Med 2019;42:361–365. doi:10.1016/j.ctim.2018.12.004
Ask AIdan what your bloods say about vitamin D, iron and the rest of the things that decide how a winter goes — before reaching for the bottle with the best story.
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