Pelargonium

Pelargonium sidoides DC. belongs to Geraniaceae, the geranium family, which SANBI’s PlantZAfrica describes as five genera: Geranium, Erodium, Monsonia, Sarcocaulon, and Pelargonium. The genus name comes from the Greek pelargos, a stork, for the long beak of the seed capsule, and sidoides refers to the resemblance of the leaves to those of Sida rhombifolia. Kew’s Plants of the World Online dates the accepted name to 1824 and lists Geranium sidifolium, described by Thunberg in 1800, among its synonyms. The genus has more than 200 species, most of them in South Africa. P. sidoides grows in short grassland, sometimes among scattered shrubs and trees, on stony soils from sand to clay-loam, shale, or basalt, in areas with 200–800 mm of mostly summer rain (PlantZAfrica). It is found from near sea level in the Eastern Cape into the mountains of Lesotho, where South Africa’s 2013 biodiversity management plan for the species records it at 2,746 m. Kew also lists KwaZulu-Natal and Eswatini in its native range, but Brendler and colleagues (Frontiers in Pharmacology 2023) state that it does not occur there.

PlantZAfrica describes a tufted, rosette-like plant with crowded, long-stalked leaves that are heart-shaped, velvety, silvery, and mildly aromatic. A description quoted in the management plan gives a height of 200–500 mm in flower, with small clusters of three to seven flowers, each 15–17 mm across, and very dark reddish-purple petals. The almost black flowers appear nearly all year but mostly from October to January, the southern summer. Underground, a system of thickened, tuberous, root-like branches lets the plant survive drought, frost, and the grass fires that sweep much of its range almost every year; it dies back in dry winters and resprouts when the rains return. Its close relative Pelargonium reniforme is very similar but has pink rather than blackish petals and a much smaller range. Neither should be confused with the bedding and balcony ‘geraniums’ that EMA calls very popular ornamentals in Europe, or with rose-scented geranium, Pelargonium graveolens, grown for its essential oil; research on the root extract does not apply to them.

The root chemistry has been studied closely. EMA’s assessment report notes that the European Pharmacopoeia defines pelargonium root as the dried underground organs of P. sidoides and P. reniforme, containing at least 2.0% tannins. The most abundant constituents are oligomeric and polymeric proanthocyanidins built mainly from catechin and gallocatechin units, together with gallic acid, its methyl ester, and a series of highly oxygenated simple coumarins, some of them present as sulfates. The best known is umckalin (PubChem CID 5316862, C11H10O5), chemically 7-hydroxy-5,6-dimethoxycoumarin, which Brendler and colleagues describe as the marker compound for P. sidoides, absent from P. reniforme. MSKCC summarizes the main constituents as polyphenols such as catechin and 7-hydroxycoumarins such as umckalin. Plant coumarins are not the drug warfarin, and EMA notes that the coumarins identified in EPs 7630 lack the chemical structure needed for anticoagulant activity. SANBI assesses the species as Least Concern on the Red List of South African Plants.

Long before it reached Europe, pelargonium root was a southern African medicine. Brendler and colleagues (Frontiers in Pharmacology 2023) trace the earliest written records: a report from around 1860 of Khoi people in the eastern Free State using the plant for unspecified ailments, an isiXhosa name, iYeza lezikhali, recorded in 1895 for dysentery with inflammation and fever, and a Sesotho name, khoaara e nyenyane, recorded in 1917 for colic. EMA’s assessment adds traditional use of the roots of both species for coughs, chest problems including tuberculosis, and diarrhea and dysentery. Charles Henry Stevens, an Englishman with tuberculosis, went to South Africa in 1897 on his doctor’s advice. In Stevens’ own account, as relayed by the Swiss physician Adrien Sechehaye, a Basotho healer in Basutoland, now Lesotho, cured him with a root he called Umckaloabo; EMA’s summary instead describes a Zulu medicine man and a boiled root preparation. Three months later Stevens considered himself cured, and back in England he sold the remedy as ‘Stevens’ Consumption Cure’.

Stevens kept his ingredient secret and advertised aggressively, by mail, in newspapers, and through anonymous books. Brendler and colleagues cite British Medical Association reports from 1909 and American Medical Association reports from 1910 and 1930 that treated him as a quack. He sued repeatedly but lost, partly because he would not reveal what his remedy contained, and he disguised its origin with claims that it came from the Gold Coast and Liberia and belonged to the buckwheat family, Polygonaceae. The cure still attracted Sechehaye, who began treating tuberculosis patients with it in 1920. EMA records that he documented about 800 patients over nine years, reported successes to the Medical Society of Geneva, and concluded that it helped many cases other than acute, malignant, or complicated ones. These were uncontrolled observations made before effective drugs existed, and once antibiotics for tuberculosis arrived, the remedy faded. In 2023 Brendler and colleagues chemically analyzed three authenticated samples of Stevens’ Cure from the Economic Botany Collection at Kew and confirmed that the ingredient was P. sidoides.

The German scientist Sabine Bladt revived the remedy in the 1970s and in 1977 named P. reniforme as its source, probably from misidentified material, since she reported umckalin, later shown to mark P. sidoides (Brendler 2023). EMA records that marketing for bronchitis and cold symptoms began in the 1970s, that Germany granted full authorization in 2005, when a mixed tincture of the two species was replaced by an extract of P. sidoides, and that the root entered the European Pharmacopoeia in 2008. Commercial success brought controversy. Root was harvested mainly from the wild in South Africa and Lesotho, and Msomi and Matthews (Africanus 2015) report estimates that harvesters were paid R3 to R15, about $0.30 to $1.50, per kilogram. In January 2010 the European Patent Office revoked a Schwabe patent on the extraction method for lack of inventive step, after opposition by the African Centre for Biosafety on behalf of a community in Alice, Eastern Cape, with the Swiss Berne Declaration. Msomi and Matthews, who interviewed members of this Masakhane community, found the decision did not oblige Schwabe to share benefits with them.

No one knows exactly how pelargonium extract works, and EMA’s 2024 assessment report is blunt that no studies of its primary pharmacology are available. Most proposed mechanisms come from cell and animal experiments. Direct antibacterial activity is real but weak. EMA summarizes work by Kayser and Kolodziej in which umckalin and a related coumarin inhibited common respiratory bacteria at 200–500 µg/ml, while EPs 7630 itself needed between 3.3 and more than 13.8 mg/ml, far higher than the thresholds usually expected of a promising antimicrobial; the assessors conclude that this activity is significantly inferior to antibiotics and cannot support an antibiotic effect. The tuberculosis legend fares no better: a P. sidoides extract inhibited Mycobacterium tuberculosis in the test tube at 100 µg/ml, against 0.06 µg/ml for the drug rifampicin, and isolated coumarins showed no antimycobacterial activity. Whatever the extract does, it does not appear to work as a herbal antibiotic, and it is not a treatment for tuberculosis.

Researchers have therefore looked at indirect effects. Michaelis and colleagues (Phytomedicine 2011) found that EPs 7630 at up to 100 µg/ml interfered with the replication of seasonal influenza A, respiratory syncytial virus, a human coronavirus, parainfluenza virus, and coxsackie virus in cell culture, but not of rhinovirus, the commonest cause of colds, adenovirus, or H5N1 avian influenza. Wittschier and colleagues (Phytomedicine 2007) showed that the extract stopped Helicobacter pylori bacteria from sticking to human stomach tissue, a model of blocking the first step of an infection, and Neugebauer and colleagues (Phytomedicine 2005) found that it increased the beat frequency of cilia, the tiny hairs that sweep mucus out of the airways, to 123–133% of baseline in cultured human nasal cells. MSKCC adds laboratory reports of increased immune signaling molecules and improved killing by white blood cells. A 2024 review by Cinatl and colleagues argues that this mix of antiviral, antibacterial, immune, and barrier effects explains the clinical results.

EMA’s assessors are more skeptical. They note that test-tube concentrations are of limited relevance to what reaches the body after a dose is swallowed, that the endotoxin content of extracts used in immune studies was not reported, and that no conclusions can be drawn from the adhesion and antiviral studies. In one animal study they cite, pretreating mice with a dry extract counteracted sickness behavior, such as listlessness and loss of appetite, triggered by a bacterial toxin. The coumarins raised a separate question about bleeding, because some coumarins are anticoagulants. Here the laboratory evidence is reassuring: Koch and Biber (Phytomedicine 2007) found that two weeks of EPs 7630 at up to 500 mg/kg did not change clotting tests in rats or alter the effect or blood levels of warfarin, and the extract’s coumarins lack the structure that anticoagulant coumarins need. EMA also suggests that the mild stomach complaints seen in trials may be due to the root’s tannins.

Acute bronchitis in adults is where most trials were done. In a representative study, Matthys and Heger (Current Medical Research and Opinion 2007) randomized 217 adults aged 18 to 66 with acute bronchitis to 30 drops of EPs 7630 solution or placebo three times a day for seven days. On a Bronchitis Severity Score covering cough, sputum, chest pain on coughing, chest sounds, and breathlessness, symptoms fell by 7.6 points with pelargonium and 5.3 points with placebo, a difference with a 95% confidence interval of 1.6 to 3.1 points. The trial was positive, but EMA’s herbal committee set a higher bar. Because acute bronchitis gets better on its own, it judged that a strong, clinically relevant effect would be a difference of at least 4 points in adults and 3 in children, and found that none of the trials reached it. It also noted that the trials came from the same investigators and the manufacturer, were done mainly in Ukraine and Russia, and did not define a clinically relevant difference in advance.

Pooled analyses are favorable but share those limitations. Cochrane’s review by Timmer and colleagues found 10 eligible trials and analyzed eight. Three trials in 746 adults with acute bronchitis showed benefit on most outcomes for the liquid preparation but not for tablets, and three trials in 819 children showed similar results; the evidence was low quality, and a funnel plot raised suspicion of publication bias. Kardos and colleagues (Multidisciplinary Respiratory Medicine 2022), a team including Schwabe researchers, pooled 11 placebo-controlled trials with 2,195 participants: by day 7, cough had stopped completely in 26.0% of adults with bronchitis taking EPs 7630 against 6.3% on placebo, and in 18.0% against 5.5% of children. Children have their own trials: Kamin and colleagues (International Journal of Clinical Pharmacology and Therapeutics 2010) treated 200 patients aged 1 to 18 for seven days, with symptom scores improving by 3.4 points against 1.2 on placebo.

Real-world results are less clear. In the PHYTOBRONCH trial, Bourqui and colleagues (npj Primary Care Respiratory Medicine 2026) randomized 332 adults with acute bronchitis in 36 Swiss family practices and five walk-in clinics to EPs 7630 or usual care, without a placebo. There was no difference in the time taken for symptoms to halve. Antibiotic use was 17.4% with pelargonium and 25.2% with usual care, a difference that was not statistically significant, and adverse events, all mild, were more frequent with pelargonium (32.3% against 21.5%). The authors called for larger trials of its possible role in reducing antibiotic use. NICE’s 2019 guideline on acute cough takes a cautious middle position: it tells clinicians that some people may wish to try pelargonium, from age 12, as a self-care treatment with limited evidence of some benefit, alongside honey and certain over-the-counter cough medicines, while stressing that most acute coughs settle within three to four weeks without antibiotics.

Common cold and sinusitis: Lizogub and colleagues (Explore 2007) gave 103 adults with cold symptoms of 24 to 48 hours’ duration 30 drops (1.5 ml) of EPs 7630 or placebo three times a day for up to 10 days. By day 10, 78.8% on pelargonium were judged clinically cured against 31.4% on placebo, and time off work averaged 6.9 against 8.2 days. A meta-analysis by Schapowal and colleagues (Heliyon 2019), with Schwabe-affiliated authors, pooled five cold trials with 833 patients and found modestly lower symptom scores and more complete recovery at days 5 and 10. Cochrane, however, could include only one cold trial, which showed benefit at day 10 but not day 5, and rated the evidence very low quality. For acute rhinosinusitis, Bachert and colleagues (Rhinology 2009) found larger symptom improvement than placebo in 103 adults given 60 drops three times a day, but Cochrane rated this single trial very low quality and found doubt about the overall effect.

Other uses are less established. In 200 people with moderate to severe COPD, Matthys and colleagues (Respiratory Medicine 2013) found that 24 weeks of add-on EPs 7630 lengthened the median time to a flare-up from 43 to 57 days, a single trial awaiting confirmation. Pelargonium has no proven role in tuberculosis, and MSKCC notes that its traditional use for dysentery and diarrhea has no scientific support. EMA’s overall judgment is that efficacy in moderate acute upper respiratory infections has not been adequately proven in adults, adolescents, or children, which is why its monograph rests on traditional use. A fair summary is that pelargonium may modestly speed recovery from acute bronchitis and perhaps colds, on evidence that is consistent but mostly manufacturer-run and of low quality. It does not treat pneumonia or any infection that needs antibiotics, and it is not a substitute for medical assessment when someone is very unwell.

Pelargonium is used almost entirely as standardized root extracts. EMA’s 2024 monograph covers a liquid extract (1 part root to 8–10 parts solvent, 11% ethanol) and two corresponding dry extracts. For the liquid, it gives 1.4 ml three times a day for adolescents over 12 and adults, 0.9 ml three times a day for children aged 6 to 12, and 0.4 ml three times a day for children aged 3 to 5. For the dry extracts, the adult dose is 20 mg three times a day, with 40 mg a day for children aged 6 to 12 and 20 mg a day for those aged 3 to 5, who should be given only liquid forms. Most adult trials used 30 drops (1.5 ml) of EPs 7630 solution three times a day for seven days in bronchitis and up to 10 days in colds. EMA advises seeing a doctor if symptoms last longer than a week or get worse.

In Germany the best-known product is Umckaloabo. In the UK, the MHRA has granted traditional herbal registrations to Schwabe’s Kaloba tablets, each containing 20 mg of EPs 7630 dry extract, and Kaloba syrup, both for symptoms of upper respiratory infections such as sore throat, cough, and blocked or runny nose, as well as to several other pelargonium products. The Kaloba syrup leaflet gives 7.5 ml three times a day from age 12 and 5 ml from 6 to 12, continued for two to three days after symptoms ease but for no longer than two weeks. Outside Europe, EMA notes, pelargonium is sold mainly as a herbal supplement, especially in North America and Mexico, including under the name Umcka (MSKCC). Most commercial root is still wild-harvested. South Africa’s 2013 biodiversity management plan found harvesting at only 6% of surveyed Eastern Cape sites, with most harvested plants resprouting, but recorded local losses where harvesting was too frequent and noted that cultivated plants take several years to produce usable roots.

Practical points: the trials enrolled people early, within 24 to 48 hours of cold symptoms or within days of a new cough, so starting late may help less. Liquid drops contain alcohol, and EMA requires ethanol labeling; its assessors suggest alcohol-free preparations for people with a history of liver disease, and alcohol is also a consideration for children, for people who avoid alcohol, and before driving. Age limits differ between products and countries, from 3 years for EU traditional products to 6 for UK Kaloba products, so follow the label rather than adult trial doses. Do not take more than one pelargonium product at a time, as it appears in combination cold remedies as well as single-herb products. Stop at once and seek medical advice if you develop yellowing of the skin or eyes, dark urine, abdominal pain, or unusual tiredness. And pelargonium is no reason to delay medical care for breathlessness, chest pain, high fever, or a cough that keeps getting worse.