The first cold of the season rarely arrives in a storm. It arrives on the first morning the radiators tick, when the windows that stood open all September are shut, and someone in the office says, “I think I'm coming down with something.” By Thursday the tissues are out. By Saturday it has a name, and the name is always the same.

Every kitchen in the Baltics has an answer ready: a black radish hollowed and filled with honey, a sauna, vitamin C by the handful, wool socks because you went out with wet hair. Some of these are right, some half right, and some simply loved. We want to sort them, with the research in hand, into three piles — what helps, what doesn't, and what is folklore — and to see how often grandmother was right.

Why the cold arrives with the cold

A cold is not caused by cold air; it is caused by a virus, most often a rhinovirus. But the old link between chill and sniffle is less foolish than it sounded. The nose is the coolest part of the airway, around 33 °C, and rhinoviruses have long been known to prefer it. In 2015 researchers at Yale showed why: in mouse airway cells, the interferon defence that normally throttles the virus worked far better at 37 °C than at a nose-temperature 33 °C, and the virus multiplied around a hundred times more at the cooler setting [1]. Breathe cold October air all day, and the front line is working at reduced power.

There is a human study to match. At Cardiff's Common Cold Centre, 180 students sat with their feet in cold water for 20 minutes, or dry in an empty bowl. Over the next four to five days, 13 of the 90 chilled students reported a cold against 5 of the 90 controls [2]. The authors' reading is the sensible one: chilling narrows the blood vessels in the nose, and in someone already quietly carrying the virus, that can be enough to let it take hold. Grandmother's socks were not nonsense.

Vitamin C: the honest ledger

Vitamin C is the remedy everyone reaches for, and it has the longest ledger. The Cochrane review by Hemilä and Chalker pooled 29 trial comparisons with 11,306 participants, and its findings are precise enough to be useful [3]. Daily vitamin C did not stop ordinary people catching colds: in the community trials the risk ratio was 0.97 — no difference. But among people under heavy physical strain — marathon runners, skiers, soldiers on subarctic exercises — it halved the number of colds, with a risk ratio of 0.48 across 598 participants. And in everyone, regular intake made colds shorter: by 8% in adults and 14% in children, across 9,745 episodes.

The same review answers the question most people actually ask: whether to start vitamin C at the first sneeze. Seven comparisons covering 3,249 cold episodes looked at exactly that and found no consistent effect [3]. The vitamin works as a standing supply, not a fire extinguisher — which moves it from the “what to take when I'm ill” pile to the “what to have in the house all winter” pile.

It also tells you where to look. The EU's authorised wording is modest and exact: vitamin C contributes to the normal function of the immune system [4]. Food is how most of us get it, and the northern autumn is generous. In a Lithuanian study of two rosehip species grown side by side, the flesh of Rosa rugosa held 736 mg of vitamin C per 100 g and Rosa canina 386 mg [5]; a pressed Rosa rugosa juice measured in Poland carried 254 mg per 100 ml [6]. Sea buckthorn from Europe's coasts carries 120–315 mg per 100 g [7] — several times what an orange offers — and we wrote about the berry in Sea Buckthorn: The Orange Berry That Makes Its Own Omega-7. Blackcurrants from eight cultivars ranged from 162 to 284 mg per 100 g [8]. And acerola, the small tropical cherry, stands an order of magnitude above citrus: 306 fruits analysed in Brazil averaged 1,834 mg per 100 g [9].

One honest footnote. Vitamin C is the most fragile thing in a fruit, and it does not wait: in a Chilean study that followed rosehip juice through eight months of storage, the ascorbic acid was gone by the sixth week in every batch, including the pasteurised, refrigerated one [10]. That is why we press quickly and keep the chain short, why a bottle, like a berry, is at its best early — and why we do not print a vitamin C figure for our juices. The number on day one is not the number on day forty.

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Zinc, and the lozenge that has to be sucked

If vitamin C is the standing supply, zinc is the one remedy with a real claim to shortening a cold once it has started — with a catch: the evidence is for lozenges dissolved slowly in the mouth, not for zinc swallowed or eaten. When Harri Hemilä pooled seven lozenge trials with 575 participants, colds were on average 33% shorter on zinc than on placebo; the zinc acetate trials gave 40%, the gluconate trials 28% [11]. The leading idea is that zinc ions released in the throat interfere with the virus where it lives.

In 2024 a new Cochrane review of the whole zinc literature — 34 studies, about 8,500 people — drew a more cautious line: zinc does not prevent colds, and as a treatment it may shorten one by about two days, with the honest warning that many trials were small and the results uncertain [12]. The two reviews disagree about the size of the effect, not its shape. Both say the same practical thing: zinc is for the first day of symptoms, as a lozenge, not something to take all winter.

Honey, ginger and the kitchen pharmacy

Now the kitchen. Honey has the best evidence of anything in the cupboard, and it is evidence for what honey has always been used for: the cough. In a trial at Penn State, 105 children aged two to eighteen with a cough from a cold were given a spoon of buckwheat honey, honey-flavoured dextromethorphan, or nothing, half an hour before bed. On every measure their parents rated — cough frequency and severity, the child's sleep and their own — honey scored best, and significantly better than no treatment [13]. A 2021 review in BMJ Evidence-Based Medicine pooled 14 randomised trials and found honey beat usual care for cough frequency, severity and overall symptoms, though in the two trials against a placebo the difference was not significant [14]. For a spoonful that costs almost nothing and tastes of summer, that is a strong record.

Ginger is the kitchen's other great warmer, and here the evidence is younger and from the laboratory. In a Taiwanese study, a hot-water extract of fresh ginger — fresh, specifically; the dried spice did not behave the same way — reduced plaque formation by respiratory syncytial virus in human airway cell lines by 20–27% at the highest dose, and worked best when the cells were treated before the virus arrived, suggesting it blocks attachment [15]. That is a cell-culture finding, not a cure. But it is a good reason to grate the root fresh rather than reach for the jar, and it fits what ginger has always been for here: heat, and a drink you can swallow when your throat is raw.

Which brings us to the Latvian classic — the black radish hollowed out, filled with honey and left overnight until the well fills with dark syrup. We will be straight with you: the honey half of that remedy has trials behind it; the radish half has none at all, in people, in animals or in a dish. What black radish does have is a long place in Central and Eastern European winter kitchens, a sharp mustard-family bite that opens the sinuses the way horseradish does, and a taste some of us would not give up for any amount of evidence.

Sleep, movement and daylight: the open door

If the kitchen remedies are about the days after the virus arrives, the strongest evidence of all is about the days before — and it concerns nothing you can buy. In 2015 researchers measured the sleep of 164 healthy adults for a week with wrist monitors, then put rhinovirus drops in their noses and quarantined them in a hotel for five days. Those who had slept five to six hours a night were 4.2 times more likely to develop a cold than those who slept more than seven; those under five hours, 4.5 times [16]. The confidence intervals are wide, but the direction is not in doubt. Sleep is the door the virus walks through; we wrote about the night's repair work in Sleep and the Second Brain.

Stress opens the same door. In the famous 1991 experiment in the New England Journal of Medicine, Sheldon Cohen's team gave 394 healthy volunteers nasal drops containing one of five cold viruses and found a clean dose–response: as psychological stress rose, the rate of clinical colds climbed from about 27% to about 47%, across every virus and after adjustment for age, sleep, smoking and personality [17].

Movement closes it a little. When 1,002 adults aged 18 to 85 kept symptom diaries through twelve autumn and winter weeks, those who did aerobic exercise five or more days a week had 43% fewer days with a cold than those who managed one day or fewer, and the fittest third had 46% fewer than the least fit [18]. An observational study, so the fit may simply be different people — but a daily walk in daylight is the cheapest remedy on this page and the only one with a view.

Daylight matters for one more reason. At our latitude the winter sun sits too low for the skin to make much vitamin D, and vitamin D is one of the few supplements with trial evidence against respiratory infections. A 2017 analysis in the BMJ pooled individual data from 10,933 people in 25 randomised trials: supplementation cut the odds of an acute respiratory infection by 12% overall, and among those who started out deficient and took it daily or weekly rather than in large occasional doses, the odds fell by 70% [19]. If one thing here is worth a conversation with your pharmacist in October, it is that.

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The folklore column: what grandmother got right

Wet hair and cold feet. Half right, and the better half. Cold does not create the virus, but the Cardiff foot-chilling study and the Yale temperature work make a respectable case that a chilled nose defends itself less well [1] [2]. Dry your hair. Wear the socks.

Chicken soup. Loved, with a laboratory footnote. In 2000 a team in Nebraska tested a grandmother's recipe in a dish and found it slowed the migration of neutrophils — the white cells whose arrival in the airway produces much of a cold's congestion — in a dose-dependent way [20]. A test-tube result, and the authors claimed nothing more. What soup certainly delivers is salt, water, warmth and the feeling of being looked after, and on day three of a cold that is not a small thing.

Black radish with honey. Honey: evidence. Radish: tradition. Keep making it if you love it — and never give the honey to a child under one year old.

Garlic. Promising and unreplicated. The one proper trial gave 146 volunteers an allicin capsule or a placebo daily for twelve winter weeks and counted 24 colds against 65 [21]. The Cochrane reviewers found it was the only trial that met their standard and asked for it to be repeated, which nobody has yet done [22]. Eat the garlic; just know it rests on a single study.

Sauna. Promising, small and very Baltic. Fifty volunteers were followed for six months, half of them taking a sauna once or twice a week; the sauna group had significantly fewer colds, concentrated in the last three months, though the colds they did catch were no shorter or milder [23]. Nobody has since run the larger trial. We take the sauna anyway.

Echinacea. Beloved, and weak on paper. Across 24 double-blind trials and 4,631 participants, no prevention trial reached significance on its own, and the reviewers' pooled estimate suggested at most a 10–20% reduction in risk, with the preparations too different to be sure of even that [24].

A fistful of vitamin C at the first sneeze. Folklore, by the vitamin's own ledger: no consistent effect once the cold has begun [3]. Take it all winter instead, preferably as fruit.

What to do this week

1. Guard the night. Seven hours is the line the sleep study drew [16]. Choose the sleep over the series.
2. Make vitamin C a standing supply, not an emergency. A glass of something tart with breakfast every day of the heating season — rosehip, sea buckthorn, blackcurrant — is the habit the evidence supports [3].
3. Keep zinc lozenges in the drawer, not the diet. They belong to the first day of symptoms, sucked slowly [11] [12].
4. Put a spoon of honey by the bed. For the night cough, for anyone over one year old, honey is the one kitchen remedy with trials behind it [13] [14]. Grate the ginger fresh when you stir it into hot water [15].
5. Walk in daylight, and ask about vitamin D. Every day you can, for as long as the light lasts [18] [19].

The first cold of the season, in short

Colds are viral, but a chilled nose defends itself less well, so grandmother's socks hold up. Regular vitamin C shortens colds by 8–14%; starting it after the first sneeze does not. Zinc lozenges on day one shorten them further, and honey eases the night cough. Short sleep multiplies the risk about fourfold, and vitamin D in a dark winter is worth asking about.

One caution: honey is never for children under one year old, and if you take anticoagulants, ask your pharmacist before making concentrated ginger a daily habit.

Back to the first morning

The radiators will tick again tomorrow, and someone will still say they are coming down with something. We cannot promise a winter without a cold; nothing on this page can. What the evidence offers is a shorter one, a rarer one, and a better night in the middle of it — and a kitchen that knew most of this before the trials were run. Dry your hair. Shut the laptop. Pour something tart with breakfast and leave the honey where you can reach it in the dark. Then let grandmother have the last word; this time she mostly earned it.

Frequently asked questions

Does vitamin C prevent colds?

For most people, no: in the Cochrane review's community trials, daily vitamin C made no difference to how many colds people caught. It did halve colds in people under heavy physical strain, such as marathon runners and soldiers in subarctic conditions, and taken regularly it shortened colds by about 8% in adults and 14% in children [3].

Should I start taking vitamin C when I feel a cold coming on?

It is too late by then. Seven trial comparisons covering 3,249 cold episodes tested vitamin C started after the first symptoms and found no consistent effect [3]. Vitamin C works as a daily supply through the winter, ideally from fruit, not as a rescue dose.

Does honey really help a cough?

Yes, better than any other kitchen remedy on record. In a trial of 105 children, a spoon of buckwheat honey before bed eased night cough and improved sleep more than no treatment, and a 2021 review of 14 randomised trials found honey reduced cough frequency and severity compared with usual care [13] [14]. Never give honey to a child under one year old.

Can you catch a cold from being cold?

Not directly — you need the virus — but cold helps it along. In a Cardiff experiment, 180 students chilled their feet in cold water for 20 minutes or kept them dry; over the next four to five days 13 of the chilled group reported a cold against 5 of the controls [2]. In the laboratory, the airway's interferon defence works less well at nose temperature than at core temperature [1].

References

1. Foxman EF, Storer JA, Fitzgerald ME, Wasik BR, Hou L, Zhao H, Turner PE, Pyle AM, Iwasaki A. Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells. Proceedings of the National Academy of Sciences of the USA. 2015;112(3):827–832. doi:10.1073/pnas.1411030112
2. Johnson C, Eccles R. Acute cooling of the feet and the onset of common cold symptoms. Family Practice. 2005;22(6):608–613. doi:10.1093/fampra/cmi072
3. Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2013;(1):CD000980. doi:10.1002/14651858.CD000980.pub4
4. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children's development and health. Official Journal of the European Union. 2012;L136:1–40.
5. Medveckienė B, Kulaitienė J, Jarienė E, Vaitkevičienė N, Hallmann E. Carotenoids, polyphenols, and ascorbic acid in organic rosehips (Rosa spp.) cultivated in Lithuania. Applied Sciences. 2020;10(15):5337. doi:10.3390/app10155337
6. Cendrowski A, Przybył JL, Studnicki M. Physicochemical characteristics, vitamin C, total polyphenols, antioxidant capacity, and sensory preference of mixed juices prepared with rose fruits (Rosa rugosa) and apple or strawberry. Applied Sciences. 2024;14(1):113. doi:10.3390/app14010113
7. Koskovac M, Cupara S, Kipic M, Barjaktarevic A, Milovanovic O, Kojicic K, Markovic M. Sea buckthorn oil — a valuable source for cosmeceuticals. Cosmetics. 2017;4(4):40. doi:10.3390/cosmetics4040040
8. Nour V, Trandafir I, Ionica ME. Ascorbic acid, anthocyanins, organic acids and mineral content of some black and red currant cultivars. Fruits. 2011;66(5):353–362. doi:10.1051/fruits/2011049
9. Moraes FP de, Costa RC, Morais CLM de, Medeiros FGM de, Fernandes TRN, Hoskin RT, Lima KMG de. Estimation of ascorbic acid in intact acerola (Malpighia emarginata DC) fruit by NIRS and chemometric analysis. Horticulturae. 2019;5(1):12. doi:10.3390/horticulturae5010012
10. Peña F, González F, Jiménez-Aspee F, Bustamante L, Ruiz A. Stability of bioactive compounds and antioxidant activity in rosehip juice (Rosa spp.). Molecules. 2024;29(11):2448. doi:10.3390/molecules29112448
11. 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;8(5):2054270417694291. doi:10.1177/2054270417694291
12. Nault D, Machingo TA, Shipper AG, Antiporta DA, Hamel C, Nourouzpour S, Konstantinidis M, Phillips E, Lipski EA, Wieland LS. Zinc for prevention and treatment of the common cold. Cochrane Database of Systematic Reviews. 2024;(5):CD014914. doi:10.1002/14651858.CD014914.pub2
13. Paul IM, Beiler J, McMonagle A, Shaffer ML, Duda L, Berlin CM Jr. Effect of honey, dextromethorphan, and no treatment on nocturnal cough and sleep quality for coughing children and their parents. Archives of Pediatrics & Adolescent Medicine. 2007;161(12):1140–1146. doi:10.1001/archpedi.161.12.1140
14. Abuelgasim H, Albury C, Lee J. Effectiveness of honey for symptomatic relief in upper respiratory tract infections: a systematic review and meta-analysis. BMJ Evidence-Based Medicine. 2021;26(2):57–64. doi:10.1136/bmjebm-2020-111336
15. Chang JS, Wang KC, Yeh CF, Shieh DE, Chiang LC. Fresh ginger (Zingiber officinale) has anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines. Journal of Ethnopharmacology. 2013;145(1):146–151. doi:10.1016/j.jep.2012.10.043
16. Prather AA, Janicki-Deverts D, Hall MH, Cohen S. Behaviorally assessed sleep and susceptibility to the common cold. Sleep. 2015;38(9):1353–1359. doi:10.5665/sleep.4968
17. Cohen S, Tyrrell DAJ, Smith AP. Psychological stress and susceptibility to the common cold. New England Journal of Medicine. 1991;325(9):606–612. doi:10.1056/NEJM199108293250903
18. Nieman DC, Henson DA, Austin MD, Sha W. Upper respiratory tract infection is reduced in physically fit and active adults. British Journal of Sports Medicine. 2011;45(12):987–992. doi:10.1136/bjsm.2010.077875
19. Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583. doi:10.1136/bmj.i6583
20. Rennard BO, Ertl RF, Gossman GL, Robbins RA, Rennard SI. Chicken soup inhibits neutrophil chemotaxis in vitro. Chest. 2000;118(4):1150–1157. doi:10.1378/chest.118.4.1150
21. Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Advances in Therapy. 2001;18(4):189–193. doi:10.1007/BF02850113
22. Lissiman E, Bhasale AL, Cohen M. Garlic for the common cold. Cochrane Database of Systematic Reviews. 2014;(11):CD006206. doi:10.1002/14651858.CD006206.pub4
23. Ernst E, Pecho E, Wirz P, Saradeth T. Regular sauna bathing and the incidence of common colds. Annals of Medicine. 1990;22(4):225–227. doi:10.3109/07853899009148930
24. Karsch-Völk M, Barrett B, Kiefer D, Bauer R, Ardjomand-Woelkart K, Linde K. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2014;(2):CD000530. doi:10.1002/14651858.CD000530.pub3

This article is for education and is not medical advice. If you have a diagnosed condition, are pregnant or take regular medication, talk to your doctor or pharmacist before changing your diet.