Most of what is written about wormwood safety is theoretical. It describes what thujone does to GABA type A receptors, quotes a regulatory threshold, and stops there. That is useful, but it leaves out the part people actually want: has anyone been hurt by this plant, and what did it look like?
A small number of published case reports answer that. They are worth reading in the original terms rather than as a general warning, because the details are more specific and more useful than the summary. Nothing here is medical advice, and wormwood has not been approved by the FDA to diagnose, treat, cure, or prevent any disease.
Key Takeaways
- A 10-month-old infant given home-prepared wormwood extract for a cold developed severe diarrhoea and persistent metabolic acidosis [1].
- A 49-year-old man was admitted in a manic state after drinking one litre of an Artemisia infusion. Serum thujone was measured at 27.7 micrograms per millilitre [2]. This is the only case where thujone was actually quantified in a patient.
- That case involved Artemisia vulgaris (mugwort), and the authors listed contamination or adulteration with another Artemisia species such as A. absinthium among the four possible explanations [2].
- A 17-year-old developed severe acute renal failure with biopsy-confirmed interstitial nephritis, attributed to chronic intake of a mixture containing wormwood, white horehound, and centaury [3].
- All three involved home-prepared or traditional preparations, not standardized commercial products. Dose was unknown in every case.
- Case reports cannot establish incidence. They establish that these outcomes are possible, which is a different and still important claim.
Why Case Reports Are Weak Evidence and Still Worth Reading
A case report is the bottom of the evidence hierarchy, and for good reason. It describes one person. There is no control group, no denominator, and usually no way to prove the substance caused the outcome rather than merely preceding it.
What a case report does well is establish possibility. Before the reports below, the statement that wormwood can cause metabolic acidosis in an infant was a theoretical inference from toxicology. After them, it is something that has been observed and documented in a clinical setting.
That matters most in exactly this situation: a botanical with no controlled human safety trials, sold without dose standardization, and used in traditional preparations whose strength varies by preparer. There is no large safety dataset to consult. These reports are the human safety data.
An Infant, a Common Cold, and a Home Preparation
The first case is the starkest, and it is the one that should change behaviour most directly.
A 10-month-old male infant was given a home-prepared Artemisia absinthium extract as a treatment for a common cold. He developed severe diarrhoea and persistent metabolic acidosis, and was reported as a poisoning case in the Journal of the Pakistan Medical Association [1].
Two features are worth isolating. The first is the indication: wormwood was given for a self-limiting viral illness that required no treatment at all. The risk was taken for no possible benefit. The second is the preparation. A home-prepared extract has no concentration control whatsoever, and thujone content in wormwood varies with chemotype, growing conditions, and how the plant is processed [4]. The preparer cannot know the dose, so neither can anyone else.
Infants are also not small adults in this context. Body weight, immature hepatic metabolism, and a much smaller margin for fluid and electrolyte loss all compound. Our article on who should avoid wormwood covers the populations where the calculation changes, and children are firmly among them.
The Case Where Thujone Was Actually Measured
The 2018 report is the most technically informative of the three, because it is the only one where the suspected toxin was quantified in the patient rather than inferred.
A 49-year-old man was admitted to a Zurich emergency department in a manic state after ingesting one litre of an infusion of Artemisia vulgaris. Investigators developed and validated an HPLC method with fluorescence detection to measure thujone in serum and urine, confirming results by gas chromatography. Serum thujone was 27.7 micrograms per millilitre on the day of admission and 24.1 the following day, confirming thujone poisoning [2].
The authors’ discussion is the useful part. They noted that adverse effects had previously been associated only with essential oil from Artemisia absinthium, attributed to inhibition of GABA receptors with consequent excitation and convulsions, and offered four possible explanations for this case: an unusually high thujone concentration in the mugwort ingested, chronic exposure, low metabolic efficiency in the patient, or contamination or adulteration of the plant material with another Artemisia species such as A. absinthium [2].
That last possibility is the reason this case belongs on a wormwood site. Species within this genus look similar, are traded loosely, and differ substantially in thujone content. A person buying loose Artemisia material is relying on the supply chain to have kept them apart. Our comparison of wormwood and wormseed covers a related identity confusion, and why third-party testing matters covers what verification actually looks like.
The other lesson is the quantity. One litre of infusion is not a teaspoon of tincture. Volume alone can convert a traditional preparation into a toxic dose.
Acute Kidney Injury From a Plant Mixture
The most recent case, published in 2024, involves a 17-year-old patient with severe acute renal failure, alongside oesophagitis with erosive gastritis and an inflammatory anaemia, with no obvious cause found on workup [3].
After other explanations were ruled out, the syndrome was attributed to chronic intake of a mixture of three medicinal plants: Artemisia absinthium, Marrubium vulgare (white horehound), and Centaurium erythraea (centaury). A renal biopsy showed interstitial nephritis without antibody deposits. The authors described it as, to their knowledge, the first reported case of acute kidney injury related to consumption of these three plants, and called for studies to assess the safety of traditional products based on them [3].
The limitation is obvious and the authors state it: three plants were taken together, so none can be individually implicated. It is entirely possible wormwood was the innocent party.
What survives that caveat is the framing in the paper’s opening, which is the broader point. The authors observe that while the nephrotoxic potential of some herbal preparations is well characterised, the use of many medicinal plants is still considered largely safe, often relying on weak evidence [3]. Absence of documented harm is not evidence of safety when nobody has looked systematically.
The contrast with the rest of wormwood’s kidney literature is worth noting. The only other renal finding of any size is a 10-patient uncontrolled pilot trial that reported reduced proteinuria in IgA nephropathy, in patients taking a thujone-free preparation under supervision. One small uncontrolled trial suggesting benefit and one case report describing harm is the entire human record for this organ, and neither design can establish cause.
What These Three Cases Have in Common
Pattern-matching across three reports is not statistics, but the shared features are still informative.
None involved a standardized commercial product. All three were home-prepared extracts, traditional infusions, or loose plant mixtures. The dose was unknown to the person taking it in every case.
All involved sustained or high-volume intake. A litre of infusion, chronic intake of a plant mixture, repeated administration to an infant. None describes a single conservative dose.
The indications were weak or absent. A common cold in the infant case, and unspecified traditional use in the others. The risk was never balanced against a benefit anyone had demonstrated.
Species identity was uncertain in at least one. The Zurich case could not exclude adulteration with a different Artemisia.
Those four features are avoidable, and avoiding them is most of what practical caution with this plant looks like: a standardized product with verified thujone content, a defined short course rather than open-ended use, a reason for taking it, and a supplier who can prove what species is in the bottle.
A Note on the Evidence
Case reports describe what happened to one person. They cannot establish how often harm occurs or at what dose, and there is no denominator. They are still the only human harm data that exists for this plant.
Frequently Asked Questions
How common is wormwood poisoning?
Nobody knows. Case reports have no denominator, so they establish that harm has occurred without indicating how often. That uncertainty is a reason for caution, not reassurance.
What happened in the infant case?
A 10-month-old boy was given a home-prepared wormwood extract for a common cold and developed severe diarrhoea with persistent metabolic acidosis [1]. Home-prepared preparations have no dose control at all.
Was thujone actually measured in any case?
In one. A 49-year-old man arrived at a Zurich emergency department in a manic state after drinking a litre of Artemisia infusion, and serum thujone was measured at 27.7 micrograms per millilitre on day zero [2]. That case involved mugwort, not wormwood, which is part of why it is instructive.
Can wormwood damage the kidneys?
One 2024 case report describes a 17-year-old with severe acute renal failure and biopsy-confirmed interstitial nephritis attributed to chronic intake of a three-plant mixture containing wormwood [3]. A three-plant mixture cannot isolate which plant was responsible.
Does this mean wormwood is unsafe at normal doses?
It does not establish that. What these reports establish is that wormwood preparations have caused serious harm in real people, that the mechanisms are plausible, and that the boundary between a traditional dose and a harmful one has never been mapped in humans.
What should I do if I have symptoms while taking wormwood?
Stop and contact a healthcare provider or poison control. Seizures, confusion, persistent vomiting or diarrhoea, or a reduction in urine output are reasons to seek care immediately rather than wait.
References
- Kocaoglu C et al. Persistent metabolic acidosis and severe diarrhoea due to Artemisia absinthium poisoning. Journal of the Pakistan Medical Association (2014). PMID 25823193
- Di Lorenzo C et al. Identification and Quantification of Thujone in a Case of Poisoning Due to Repeated Ingestion of an Infusion of Artemisia vulgaris L. Journal of Food Science (2018). PMID 30044501
- Selles A et al. Acute Kidney Injury Following the Ingestion of a Medicinal Plants Mixture: A Case Report. Case Reports in Nephrology (2024). PMID 39735399
- Lachenmeier DW. Wormwood (Artemisia absinthium L.), a curious plant with both neurotoxic and neuroprotective properties? Journal of Ethnopharmacology (2010). PMID 20542104
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.