A new study led by the University of Fribourg, in collaboration with the Universities of Lausanne and Geneva, raises serious concerns about the quality and safety of plant-based dietary supplements containing green chiretta (Andrographis paniculata). The researchers found that most products currently on sale in Switzerland — and widely available internationally — are poorly manufactured, inaccurately labelled, and in some cases contaminated with toxic substances.

Since the COVID-19 pandemic, sales of Andrographis paniculata supplements, commonly marketed for respiratory infections, have surged worldwide. Because these products are sold as dietary supplements rather than medicines, they are not subject to the stringent quality, safety, and efficacy standards required for pharmaceuticals. As a result, consumers are largely left unprotected.

Misleading labels and toxic contaminants
The research team analysed 40 Andrographis paniculata supplements purchased in 13 countries, including 27 products available online to Swiss consumers. Using state-of-the-art phytochemical analyses, they found that:

• only two products contained the amount of andrographolide (the main active compound) stated on the label;
• twenty products were under-dosed, while one was over-dosed;
• three online products were contaminated with toxic substances, including mercury and banned pesticides such as strychnine and butralin.

“These findings show that many consumers are buying products that simply do not match what is promised on the label — sometimes with real risks to their health,” says Angélique Bourqui, pharmacist at the University of Fribourg and first author of the study. “The quality gap between authorised herbal medicines and dietary supplements is striking and exposes a serious regulatory blind spot.”

Weak regulation, higher risk
Unlike regulated herbal medicines, plant-based dietary supplements do not require proof of safety, efficacy, or quality before entering the market in Switzerland, Europe, or the United States. Post-marketing surveillance is minimal or non-existent.

Products purchased online posed the greatest concern, accounting for all cases of contamination with heavy metals or banned pesticides.

“Buying herbal supplements online can carry substantial risks,” warns Professor Pierre-Yves Rodondi, co-author of the study and Professor of Family Medicine at the University of Fribourg. “Without appropriate regulation or independent quality control, consumers have no reliable way of knowing what they are actually ingesting.”

What this means for consumers and clinicians

“‘Natural’ does not automatically mean ‘safe’,” Professor Rodondi emphasises. “Under-dosed products may be ineffective, while contaminated ones can be actively harmful.”

The researchers call for several urgent measures:

• Stronger quality controls, including independent certification systems to verify product composition and purity.
• A balanced regulatory approach combining clearer labelling, independent testing, and better public information, without disadvantaging small producers.
• Improved awareness among healthcare professionals, who should routinely ask patients about supplement use, particularly in cases of unexplained symptoms or suspected toxicity.

“Our findings do not suggest that plant-based products should be avoided altogether,” Professor Rodondi concludes. “They underline the need for transparent, verifiable quality standards. Switzerland has an opportunity to take a leading role in improving consumer protection in this rapidly expanding global market.”