What actually calms a cough: honey, herbs, steam, or syrups?

Time does most of the work

Most coughs follow a cold or other viral infection and fade by themselves. Across studies of otherwise healthy adults, the average cough lasted 17.8 days, while people surveyed expected about a week. The authors argue that this mismatch feeds antibiotic overuse for coughs¹⁰.

Honey

For children aged 12 months and over, honey probably reduces cough more than no treatment or placebo, and may do about as well as dextromethorphan. Most trials gave one night's dose, and the review authors saw no strong evidence either way¹. In single-dose trials, parents rated honey better than no treatment among 105 children aged 2 to 18, and better than a date-syrup placebo among 300 children aged 1 to 5^2,3. A newer Japanese trial of 161 children aged 1 to 5 found honey no better than a honey-flavored syrup⁴. A 2021 meta-analysis of 14 studies found honey beat usual care for cough frequency and severity, but placebo-controlled data were limited¹². Honey must never be given to babies under 12 months⁵.

Herbal syrups

An updated review of ivy leaf trials found that all favored it, but the effects were minimal and of uncertain clinical importance, with a high risk of bias⁹. A thyme-ivy syrup cut coughing fits by 68.7% versus 47.6% on placebo in 361 adults with acute bronchitis⁸. Liquid Pelargonium sidoides extracts helped bronchitis symptoms in low-quality trials; side effects were more common with the extract but not serious⁷. See Pelargonium sidoides, and which herbs interact with medications.

Shop-bought cough medicines

A Cochrane review of 29 trials (4,835 people) found no good evidence for or against over-the-counter cough medicines. In children, cough suppressants, antihistamines and antihistamine-decongestants were no better than placebo, and the authors warned that some of these drugs can cause serious harm in children⁶.

When a cough needs a clinician

Guidelines call a cough chronic after 8 weeks in adults and 4 weeks in children, and it needs assessment. In a healthy toddler, a sudden cough may mean an inhaled object. In children, coughing up blood, breathlessness, chest pain and poor growth are listed as signs of a specific cause, and in adults the guideline advises checking for infection, malignancy and ACE inhibitor use (a blood-pressure drug)¹¹. For steam, see does breathing steam help a cold.

Honey

The 2018 Cochrane review pooled six randomized trials in 899 children aged 12 months to 18 years. On a 7-point scale, honey lowered cough frequency by a mean difference of -1.05 against no treatment (95% CI -1.48 to -0.62; 154 children; moderate certainty) and -1.62 against placebo (95% CI -3.02 to -0.22; 402 children). It did not differ clearly from dextromethorphan (mean difference -0.07; low certainty) and may have beaten diphenhydramine (-0.57; one study of 80 children; low certainty). Beyond three days, honey had no advantage over placebo or salbutamol¹. Paul and colleagues randomized 105 children aged 2 to 18 with colds to buckwheat honey, honey-flavored dextromethorphan or nothing. Honey was better than no treatment for cough frequency and the combined score; dextromethorphan was not better than no treatment on any outcome, and honey and dextromethorphan did not differ significantly². Cohen and colleagues randomized 300 children aged 1 to 5 to 10 g of eucalyptus, citrus or labiatae honey or a date-extract placebo; every group improved overnight, but improvement was greater with honey³. The 2021 meta-analysis of 14 studies reported a mean difference of -3.96 on a combined symptom score (3 studies), and standardized differences of -0.36 for cough frequency (8 studies) and -0.44 for severity (5 studies) against usual care; the two studies against placebo were not significant (-0.63; 95% CI -1.44 to 0.18)¹².

Where honey results conflict

The pediatric trials mostly relied on parent ratings after one or two nights, and every group, placebo included, improved as the illness ran its course. In the Japanese multicenter trial, 78 children got acacia honey and 83 a honey-flavored syrup for two nights; both improved, with no significant difference⁴. One possible explanation is that the placebos were themselves sweet syrups, so part of any soothing effect was shared by both arms. The Cochrane authors concluded there was no strong evidence for or against honey¹.

Herbal products

Kemmerich and colleagues ran an 11-day double-blind trial in 361 adults with acute bronchitis, comparing thyme-ivy syrup (n=182) with placebo (n=179). Coughing fits fell by 68.7% on days 7 to 9 versus 47.6% on placebo (p<0.0001), a 50% reduction came two days sooner, and responder rates were 96.2% versus 74.7% at the end of treatment; there were no serious adverse events⁸. The updated ivy leaf review found six randomized trials, one controlled trial and four observational studies; all favored ivy, three randomized trials showed faster improvement, but reporting quality was low and the clinical significance minimal⁹. The Pelargonium Cochrane review included eight of ten eligible trials. Three trials in 746 adults and three in 819 children with acute bronchitis favored the liquid extract but not tablets, and the authors rated the evidence low quality and suspected publication bias. One sinusitis trial (103 adults) showed a significant effect on complete resolution at day 21 (RR 0.43, 95% CI 0.30 to 0.62), at very low quality⁷.

Over-the-counter medicines

Smith and colleagues could not pool 29 placebo-controlled trials (19 in adults, 10 in children) because they differed too much. In adults, results were variable: one of three guaifenesin trials showed benefit, and three trials found antihistamines no better than placebo. In children, cough suppressants (three trials), antihistamines (three) and antihistamine-decongestants (two) were no better than placebo. Adverse effects were more common with antihistamine and dextromethorphan products⁶.

How long and how worrying

Ebell and colleagues surveyed 493 adults and found a median expected cough duration of 5 to 7 days, while the systematic review of published studies found a mean of 17.8 days¹⁰. The European Respiratory Society guideline notes that recent guidelines use 8 weeks in adults and 4 weeks in children as the threshold for chronic cough, describes foreign body inhalation as a cause of sudden cough in healthy preschool children, and advises excluding infection, malignancy and ACE inhibitor use in adults¹¹.

Bottom line

Confidence is moderate to low (3 of 5). Honey probably gives modest relief of night cough in children over one year^1,2,3, though a recent trial did not reproduce it⁴. Ivy, thyme and Pelargonium products may help slightly, based on low-quality trials^7,8,9. Over-the-counter cough medicines lack good evidence⁶. Time, and attention to red flags, matter most^10,11.