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Supplements for Bronchitis: NAC, Pelargonium, Honey, and What to Skip

Supplements for bronchitis depend on the type. In chronic bronchitis or COPD, oral N-acetylcysteine (NAC) taken daily for months cut flare-ups modestly in meta-analyses (grade B), though recent large trials disagree and it did not slow lung-function decline. For acute bronchitis, a chest infection whose cough lasts 2 to 3 weeks, a liquid pelargonium root extract eased symptoms (grade B) and honey eased cough (grade C). None replaces inhalers or a check for pneumonia.

Published How we grade evidenceEditorial policy

The short version

  • NAC for chronic bronchitis or COPD flare-ups: taken by mouth for months, about a quarter fewer flare-ups in pooled trials, but trials of 523 and 968 people found no clear drop. Grade B (Cazzola 2015; Decramer 2005; Zhou 2024).
  • NAC for lung function: no clear difference in the main breathing test. Grade B (Decramer 2005; Zhou 2024).
  • NAC for acute bronchitis: no adult trial found. Grade D (Smith 2014).
  • Liquid pelargonium root extract for acute bronchitis: lower symptom scores, though the evidence is rated low. Grade B (Timmer 2013).
  • Honey for cough: less frequent, milder cough than usual care in colds and similar infections. Grade C (Abuelgasim 2021).
  • Ivy leaf and andrographis: small effects on cough in poor-quality trials. Grade C (Sierocinski 2021; Hu 2017).

There are two kinds of bronchitis, and the evidence differs. Acute bronchitis is a short-lived inflammation of the windpipe and large airways, usually from a virus, and its cough runs about 2 to 3 weeks (Kinkade 2016). Antibiotics barely shorten it: in 7 trials with 2,776 people, the cough was 0.46 days shorter on them (Smith 2017).

Chronic bronchitis is a long-term cough with mucus, linked mainly to smoking and to dust or fumes at work (Zhang 2024). It often comes with COPD (chronic obstructive pulmonary disease, airways that stay narrowed). Its trials count flare-ups (exacerbations): at least 2 days of worse cough, mucus, wheeze or breathlessness (Zhou 2024).

Does NAC cut flare-ups in chronic bronchitis or COPD?

Grade B. NAC (N-acetylcysteine) is a form of the amino acid cysteine that thins mucus. A 2015 meta-analysis pooled 13 studies with 4,155 people taking oral NAC or a comparison; flare-ups were about a quarter less common on NAC (relative risk 0.75), most clearly in people whose breathing tests showed no narrowing (Cazzola 2015). In an older review, across the 9 trials that counted it, 48.5% on NAC stayed flare-up free over 12 to 24 weeks, against 31.2% on placebo (Stey 2000).

A Cochrane review of mucus-thinning pills (NAC plus related medicines such as carbocysteine, erdosteine and ambroxol) found that, in the 28 trials that reported it (6,723 people), treating 8 people for about nine months kept one more person free of flare-ups. Longer and newer trials showed smaller effects (Poole 2019).

The newest evidence is split. A 2023 meta-analysis of placebo-controlled trials published since 2000 found no clear difference in how many people stayed flare-up free (Huang 2023). A 2024 analysis of 20 studies found fewer flare-ups in COPD (incidence rate ratio 0.76) and in chronic bronchitis without COPD (0.81), though its abstract doesn't say how the NAC was given (Papi 2024).

Does a higher dose matter?

The trials used 600 mg once a day or 600 mg twice a day (1,200 mg), and the results don't sort neatly by dose:

  • 600 mg once a day: in 523 people with COPD followed for 3 years, flare-ups (1.25 against 1.29 a year) did not differ from placebo (Decramer 2005).
  • 600 mg twice a day, moderate to severe COPD: in a 1-year trial at 34 hospitals in China (1,006 people), flare-ups fell from 1.49 to 1.16 per person per year; a drug company funded it, and some authors worked there (Zheng 2014). A 1-year Hong Kong trial in 120 people found 0.96 against 1.71 flare-ups a year, with no change in breathlessness or quality of life (Tse 2013).
  • 600 mg twice a day, mild to moderate COPD: in 968 people over 2 years, the rate was 0.65 against 0.72 a year, not a clear difference (Zhou 2024).

The 2015 meta-analysis advised at least 1,200 mg a day when breathing tests show narrowing, and 600 mg without it (Cazzola 2015), while the Cochrane review found that dose didn't seem to change the effect (Poole 2019). All four trials gave NAC as tablets by mouth (Cazzola 2015; Tian 2020).

Does NAC improve lung function?

Grade B. No clear difference. In the 3-year trial, FEV1 (how much air you can blow out in one second) fell by 54 mL a year on NAC and 47 mL on placebo, no real difference (Decramer 2005). The 2-year trial and the 2023 meta-analysis also found no FEV1 difference (Zhou 2024; Huang 2023); only the small Hong Kong trial saw better small-airway tests (Tse 2013). Our database page shows lung function as "improves" on 50 people; the larger trials don't support that.

Does NAC help acute bronchitis or a chest cold?

Grade D. No trial we found tested NAC against a placebo in adults with a new chest infection. A Cochrane review of over-the-counter cough medicines found one adult trial in which an unnamed mucus thinner cut cough frequency and symptom scores (Smith 2014). The B grade on our acute bronchitis page and protocol rests on a meta-analysis in chronic bronchitis (Wei 2019), so it doesn't carry over to a cough that clears within weeks.

Does pelargonium (umckaloabo) help acute bronchitis?

Grade B. Pelargonium sidoides is a South African geranium whose root extract has the most bronchitis trials. In one, 124 adults took 30 drops of the liquid or a placebo three times a day for 7 days. Their bronchitis symptom score fell 7.2 points against 4.9, and 68.8% noticed it working within 4 days, against 33.3% (Chuchalin 2005).

Tablets are less clear-cut. In 406 adults, 20 or 30 mg tablets three times a day lowered the score by about 6 points, against 2.7 on placebo (Matthys 2010), yet the Cochrane review found the tablet trials ineffective for most outcomes, unlike the liquid (Timmer 2013). A 2022 analysis of the extract's trials found 26.0% of adults with acute bronchitis had stopped coughing by day 7, against 6.3% on placebo; three of its seven authors worked for the maker (Kardos 2022).

Our database page grades pelargonium A. We grade it B because the Cochrane reviewers rated the evidence low and suspected missing negative trials (Timmer 2013), and all six trials in a 2008 review tested the same extract (Agbabiaka 2008).

Grade C for COPD flare-ups: in one trial, 200 adults with moderate to severe COPD took 30 drops three times a day or a placebo for 24 weeks alongside usual care; the median time to a first flare-up was 57 days against 43 (Matthys 2013).

Does honey help a bronchitis cough?

Grade C. Pooling 14 studies of colds and similar nose and throat infections, a 2021 review found honey lowered cough frequency (8 studies) and cough severity (5 studies) compared with usual care. Only 2 studies used a placebo, and together they showed no clear difference (Abuelgasim 2021). None was limited to bronchitis. For a child, ask a clinician; never give honey to a baby under 12 months, because it can cause botulism, a severe food poisoning (CDC).

Do ivy leaf or andrographis help the cough?

Grade C. A 2021 update found 6 randomized trials of ivy leaf extract for cough from colds and bronchitis. Half reported a faster drop in cough, but the authors judged the benefit of uncertain clinical importance and the trials poorly reported and open to bias (Sierocinski 2021).

Grade C. Andrographis, an Asian herb, was tested in 33 trials of acute respiratory infections. In the trials pooled for cough against a placebo (596 people), cough scores improved modestly, but the reviewers rated the trials' quality poor overall (Hu 2017).

Do vitamin C, zinc, elderberry or echinacea help bronchitis?

Grade D. For vitamin C we found two small trials. In 57 older adults in hospital with bronchitis or bronchopneumonia, 200 mg a day by mouth gave better symptom scores than placebo, most clearly in the sickest (Hunt 1994). In 100 people with chronic bronchitis, 500 mg twice a day for 3 months, alone or with NAC, changed neither breathing tests nor symptoms (route not stated) (Lukas 2005).

We found no bronchitis trials of zinc, elderberry or echinacea. Their trials are in colds and flu, a different illness (Nault 2024; Wieland 2021; Karsch-Völk 2014).

Does vitamin D help chronic bronchitis or COPD?

Grade B. Pooling individual data from 3 trials (469 people with COPD), vitamin D did not lower the overall rate of moderate or severe flare-ups (rate ratio 0.94). In a planned subgroup whose blood level started below 25 nmol/L, flare-ups were about half as frequent (rate ratio 0.55); above that level there was no effect (Jolliffe 2019). A blood test shows which group you're in.

What we'd skip

  • NAC for a short chest cold. No adult trial supports it.
  • Inhaled or nebulized NAC at home. It's a prescription form whose label warns it can tighten airways, especially in asthma (FDA-approved label on DailyMed). The oral trials don't apply to it.
  • Zinc, elderberry and echinacea sold "for bronchitis." No bronchitis trials.
  • "Lung support" blends. We found no trials of multi-ingredient blends.

Safety and interactions

  • NAC by mouth: stomach and gut side effects were about as common as on placebo (10.2% against 10.9%) (Stey 2000); over 1 year, 29% on NAC and 26% on placebo reported any (Zheng 2014).
  • NAC with nitroglycerin: in 200 people with unstable angina, oral NAC plus a nitroglycerin patch caused side effects in 35%, mostly severe headache, almost twice as often as the patch alone (Ardissino 1997). If you use nitrates for chest pain, ask your prescriber first.
  • NAC and asthma: given into a vein for acetaminophen poisoning, NAC can cause allergy-like reactions, including bronchospasm (sudden airway tightening), more often in people with asthma (Sandilands 2009), and the inhaled form carries a bronchospasm warning (DailyMed). With asthma, ask a clinician before trying NAC.
  • NAC's legal status: as of 7 November 2026, the FDA holds that NAC is excluded from the dietary supplement definition because it was approved as a drug first, but under final guidance from August 2022 it does not act against otherwise lawful NAC supplements; in November 2023 it said its safety review was complete (FDA guidance; FDA update).
  • Pelargonium: mild side effects rose with dose in the tablet trial (Matthys 2010), and minor digestive complaints were more frequent over 24 weeks in COPD (Matthys 2013). Of 13 liver-injury cases first blamed on it, a causality review could tie none to it (Teschke 2012); in a Berlin hospital study of 198 liver-injury cases, one was rated a possible link (Douros 2016). If your eyes or skin turn yellow or your urine darkens, stop it and get checked. No interaction studies were found for pelargonium or ivy leaf.
  • Zinc: the adult upper limit is 40 mg a day from all sources (NIH ODS); in cold trials it caused more minor side effects than placebo (Nault 2024). Andrographis side effects were mostly minor and digestive (Hu 2017).

When to see a doctor

  • Right away: trouble breathing, wheezing, chest pain, coughing up blood, blue lips, or confusion.
  • Soon: a fever that lasts more than a few days. A doctor can rule out pneumonia, which acute bronchitis can resemble (Kinkade 2016).
  • A cough past 3 weeks. Guidelines call a cough under 3 weeks acute and over 8 weeks chronic, with other causes to look for, such as asthma or reflux (Irwin 2018).
  • Coughing fits that end in a whoop or vomiting after 2 weeks can be whooping cough (Kinkade 2016).
  • A cough with mucus most days that keeps coming back. Ask for a breathing test (spirometry) to check for COPD.
  • If you have COPD, asthma, heart failure or a weak immune system, call early when symptoms change.

Don't stop a prescribed medicine on your own, including inhalers; ask the prescriber or pharmacist. In the trials, NAC was an add-on, not a substitute. If you are pregnant, breastfeeding or under 18, ask a clinician.

FAQ

What is the best supplement for bronchitis? For chronic bronchitis or COPD, oral NAC has the best support, for fewer flare-ups (grade B). For acute bronchitis, liquid pelargonium root extract (grade B) and honey for cough (grade C) lead.

Does NAC help with bronchitis mucus? Taken daily for months, NAC modestly reduced chronic bronchitis flare-ups (grade B). We found no adult trial in acute bronchitis (grade D).

How much NAC did the trials use? 600 mg once or twice a day by mouth, for 3 months to 3 years. Twice a day helped in one large trial in moderate to severe COPD but not in another in milder COPD.

Is NAC still sold as a dietary supplement in the US? Yes. As of 7 November 2026, the FDA regards NAC as a drug ingredient but, since August 2022, does not act against otherwise lawful NAC supplements.

Are lung support supplements independently tested? We found no published trials of multi-ingredient lung support blends. Outside lab testing can check what a bottle contains, not whether it helps.

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