Sweet Wormwood

In Chinese medicine the herb is qinghao. Shennong’s Herbal Classic (around 100 CE) describes it as bitter and cold, and lists it for scabies, itching, sores and lice, for heat retained in the bones, and for improving vision ^{26Reference 26Sun et al. · 2025ReviewArtemisiae Annuae Herba: from anti-malarial legacy to emerging anti-cancer potential — reviewView study →}.

Its use against malaria was recorded by the physician Ge Hong (283–343 CE), who instructed that the herb be soaked in water and its juice wrung out ^{26Reference 26Sun et al. · 2025ReviewArtemisiae Annuae Herba: from anti-malarial legacy to emerging anti-cancer potential — reviewView study →}. His Handbook of Prescriptions for Emergencies reads: “A handful of qinghao immersed in two litres of water, wring out the juice and drink it all” ^{25Reference 25Gu et al. · 2017ReviewInnovating Chinese herbal medicine: from traditional health practice to scientific drug discovery — reviewView study →}. The Song dynasty scholar Zhou Qufei (1134–1189) also recorded it as a key treatment for malaria ^{26Reference 26Sun et al. · 2025ReviewArtemisiae Annuae Herba: from anti-malarial legacy to emerging anti-cancer potential — reviewView study →}.

In 1971, Tu Youyou and her colleagues turned to qinghao in their search for an antimalarial. Ge Hong’s cold preparation suggested to her that heating might destroy the active molecule. Her team switched to a low-temperature ethyl ether extraction, and the new extract inhibited rodent malaria by 95–100% ^{25Reference 25Gu et al. · 2017ReviewInnovating Chinese herbal medicine: from traditional health practice to scientific drug discovery — reviewView study →}.

Artemisinin’s endoperoxide bridge reacts with the haem and ferrous iron released as the parasite digests haemoglobin inside the red blood cell ^{26Reference 26Sun et al. · 2025ReviewArtemisiae Annuae Herba: from anti-malarial legacy to emerging anti-cancer potential — reviewView study →}.

In 14 healthy men, one litre of tea made from 9 g of leaves contained 94.5 mg of artemisinin, about 19% of the usual daily dose. Artemisinin was absorbed faster from the tea than from tablets, with similar bioavailability. The authors judged the blood levels enough for a clinical effect but not enough to substitute for artemisinin drugs ^{1Reference 1Räth et al. · 2004Clinical trialPharmacokinetic study of artemisinin after oral intake of a traditional preparation of Artemisia annua L. (annual wormwood) — clinical trialView study →}.

In an open randomised trial in uncomplicated malaria, tea preparations cleared parasites and symptoms quickly. Seven-day cure rates averaged 74%, against 91% for quinine, but many infections returned ^{2Reference 2Mueller et al. · 2004RCTRandomised controlled trial of a traditional preparation of Artemisia annua L. in the treatment of malaria — randomised controlled trialView study →}.

In a double-blind trial in semi-immune adults, tea and sulfadoxine-pyrimethamine both cured 7 of 10 and 7 of 9 patients at day 7. By day 28, cure rates had fallen to 1 of 9 with the tea and 3 of 8 with sulfadoxine-pyrimethamine ^{3Reference 3Blanke et al. · 2008RCTHerba Artemisiae annuae tea compared to sulfadoxine-pyrimethamine in uncomplicated falciparum malaria — randomised double-blind clinical trialView study →}.

In mice with rodent malaria, a single dose of dried whole leaf reduced parasites more effectively than a comparable dose of pure artemisinin ^{4Reference 4Elfawal et al. · 2012AnimalDried whole plant Artemisia annua as an antimalarial therapy — mouse in vivo modelView study →}. In lab tests against P. falciparum, extracts from flavonoid-free mutant plants were as active as normal extracts, while extracts from plants that could not make artemisinin had little or no activity ^{5Reference 5Czechowski et al. · 2019In vitroFlavonoid versus artemisinin anti-malarial activity in Artemisia annua whole-leaf extracts — in vitroView study →}.

Artemisinin is prescribed only in combination therapies, to limit the spread of resistance ^{4Reference 4Elfawal et al. · 2012AnimalDried whole plant Artemisia annua as an antimalarial therapy — mouse in vivo modelView study →}. Partial resistance, driven mainly by mutations in the parasite’s Kelch13 gene, has now emerged in Africa ^{6Reference 6Ward et al. · 2022ReviewPlasmodium falciparum resistance to artemisinin-based combination therapies — reviewView study →}. The WHO does not support using Artemisia plant material in any form to prevent or treat malaria ^{24Reference 24World Health Organization · 2019The use of non-pharmaceutical forms of Artemisia — position statement and technical document (WHO/CDS/GMP/2019.14). https://www.who.int/publications/i/item/WHO-CDS-GMP-2019.14View study →}.

Gap: a large double-blind trial reporting that Artemisia tea beat artesunate-amodiaquine was retracted ^{7Reference 7Munyangi et al. · 2020Retraction notice: Artemisia annua and Artemisia afra tea infusions vs. artesunate-amodiaquine in treating P. falciparum malariaView study →}. No adequately powered, unretracted trial shows the herb cures malaria without the infection returning.

Artemisinin-type drugs have shown anticancer activity in preclinical models, through proposed mechanisms including DNA damage, blocking new blood-vessel growth, and triggering cell death ^{9Reference 9Deeken et al. · 2018Clinical trialA phase I study of intravenous artesunate in patients with advanced solid tumour malignancies — clinical trialView study →}.

The human data belong to the isolated derivative artesunate, not to A. annua. In a double-blind, placebo-controlled pilot trial, 23 people awaiting colorectal cancer surgery took 200 mg of oral artesunate or placebo daily for 14 days. The primary outcome, tumour-cell apoptosis, was similar in both groups (67% vs 55% of patients). A Bayesian analysis gave a 0.89 probability that artesunate reduced the proliferation marker Ki67. Over a median 42 months, cancer returned in 1 patient on artesunate and 6 on placebo ^{8Reference 8Krishna et al. · 2015RCTA randomised, double-blind, placebo-controlled pilot study of oral artesunate therapy for colorectal cancer — randomised controlled trialView study →}.

A phase I trial of intravenous artesunate in advanced solid tumours set a maximum tolerated dose of 18 mg/kg. There were no tumour responses, and 27% of patients had stable disease ^{9Reference 9Deeken et al. · 2018Clinical trialA phase I study of intravenous artesunate in patients with advanced solid tumour malignancies — clinical trialView study →}.

In metastatic breast cancer, oral artesunate added to standard treatment was well tolerated at up to 200 mg a day over four weeks ^{10Reference 10von Hagens et al. · 2017Clinical trialPhase I study to define a well-tolerated dose of oral artesunate as add-on therapy in metastatic breast cancer (ARTIC M33/2) — clinical trialView study →}, and 13 patients continued for up to 37 months without major safety concerns ^{11Reference 11von Hagens et al. · 2019Clinical trialLong-term add-on therapy (compassionate use) with oral artesunate in metastatic breast cancer — clinical trialView study →}.

Self-administered vaginal artesunate inserts led to regression of CIN2/3 cervical lesions in 19 of 28 women ^{12Reference 12Trimble et al. · 2020Clinical trialFirst-in-human proof-of-concept trial of intravaginal artesunate to treat cervical intraepithelial neoplasia 2/3 — clinical trialView study →}.

Gap: every human result is for the semi-synthetic drug, mostly in early-phase, uncontrolled trials. There is no controlled human trial of the whole herb for any cancer.

Water, methanol, ethanol and acetone extracts of A. annua all reduced LPS-induced nitric oxide, prostaglandin E2 and inflammatory cytokines, with the acetone extract most active ^{16Reference 16Kim et al. · 2015In vitroAnti-inflammatory, antioxidant and antimicrobial effects of artemisinin extracts from Artemisia annua L. — in vitroView study →}.

In broiler chickens, an aqueous extract added to feed lowered intestinal IL-1β and IL-6 through the NF-κB pathway ^{13Reference 13Guo et al. · 2022AnimalArtemisia annua L. aqueous extract promotes intestinal immunity and antioxidant function in broilers — animal modelView study →}.

Gap: no human anti-inflammatory trial of the herb. Much of the animal data comes from production livestock rather than disease models.

The ethanol extract of A. annua scavenged 91% of free radicals in vitro, close to α-tocopherol ^{16Reference 16Kim et al. · 2015In vitroAnti-inflammatory, antioxidant and antimicrobial effects of artemisinin extracts from Artemisia annua L. — in vitroView study →}.

In broiler chickens, an aqueous extract in feed raised antioxidant enzyme activity in the small intestine through the Nrf2 pathway ^{13Reference 13Guo et al. · 2022AnimalArtemisia annua L. aqueous extract promotes intestinal immunity and antioxidant function in broilers — animal modelView study →}.

Gap: no human antioxidant study of the herb.

The clearest autoimmune signal comes from SM934, a water-soluble artemisinin analogue. In lupus-prone MRL/lpr mice, oral SM934 reduced proteinuria, kidney damage and anti-dsDNA antibodies and extended survival, by suppressing Th1 and Th17 responses and increasing regulatory T cells ^{14Reference 14Hou et al. · 2011AnimalOral administration of artemisinin analogue SM934 ameliorates lupus syndromes in MRL/lpr mice by inhibiting Th1 and Th17 responses — mouse modelView study →}.

In a mouse model of lupus with antiphospholipid syndrome, it reduced autoantibodies, inflammation and oxidative stress in the kidney through Nrf2 signalling ^{15Reference 15Lin et al. · 2021AnimalArtemisinin analogue SM934 protects against lupus-associated antiphospholipid syndrome via activation of Nrf2 — mouse modelView study →}.

A review collects the anti-inflammatory and immunoregulatory effects of artemisinin drugs across autoimmune and transplant models ^{17Reference 17Qiu et al. · 2021ReviewImmunoregulation by artemisinin and its derivatives: a new role for old antimalarial drugs — reviewView study →}.

Gap: the strongest data use a synthetic analogue (SM934) that the herb does not contain, in rodents. There is no controlled human trial of A. annua or artemisinin for any autoimmune disease.

Artemisinin and its derivatives are active in vitro and in animals against several other protozoa, including Leishmania, trypanosomes, Toxoplasma and Giardia, and against schistosomes ^{18Reference 18Loo et al. · 2017ReviewArtemisinin and its derivatives in treating protozoan infections beyond malaria — reviewView study →}.

A large clinical trial reporting that A. annua tea cleared Schistosoma mansoni eggs faster than praziquantel was retracted ^{21Reference 21Munyangi et al. · 2020Clinical trialRetraction notice: Effect of Artemisia annua and Artemisia afra tea infusions on schistosomiasis in a large clinical trialView study →}.

Gap: the human evidence for the herb in schistosomiasis was withdrawn. The remaining data are from animals and cell cultures.

Artemisinin and artesunate inhibit several viruses in vitro, including human cytomegalovirus, herpes simplex, Epstein-Barr, hepatitis B and hepatitis C ^{19Reference 19Efferth et al. · 2008ReviewThe antiviral activities of artemisinin and artesunate — reviewView study →}.

Against SARS-CoV-2 in cell culture, artesunate was the most potent compound tested (EC50 7–12 µg/mL), followed by artemether, A. annua extracts (83–260 µg/mL) and artemisinin. The safety margins in cells were mostly narrow ^{20Reference 20Zhou et al. · 2021In vitroIn vitro efficacy of artemisinin-based treatments against SARS-CoV-2 — in vitroView study →}.

In a second study, hot-water extracts of seven A. annua cultivars inhibited SARS-CoV-2 and two variants. Their activity did not track their artemisinin or flavonoid content, and the authors concluded that something other than artemisinin was probably responsible ^{22Reference 22Nair et al. · 2021In vitroArtemisia annua L. extracts inhibit the in vitro replication of SARS-CoV-2 and two of its variants — in vitroView study →}.

Gap: entirely in vitro, with no human efficacy data.

Ethanolic and aqueous extracts and the essential oil of A. annua inhibited multidrug-resistant E. coli in vitro, with the essential oil most potent ^{23Reference 23Golbarg et al. · 2021In vitroAntibacterial potency of medicinal plants including Artemisia annua against multidrug-resistant E. coli — in vitroView study →}. Extracts were also active against several bacteria that cause gum disease ^{16Reference 16Kim et al. · 2015In vitroAnti-inflammatory, antioxidant and antimicrobial effects of artemisinin extracts from Artemisia annua L. — in vitroView study →}.

Gap: laboratory activity only, with no clinical data.

Malaria treatment. Artemisinin is prescribed only in combination with a second antimalarial, to limit resistance ^{4Reference 4Elfawal et al. · 2012AnimalDried whole plant Artemisia annua as an antimalarial therapy — mouse in vivo modelView study →}. Partial resistance, driven mainly by Kelch13 mutations, has emerged in Africa ^{6Reference 6Ward et al. · 2022ReviewPlasmodium falciparum resistance to artemisinin-based combination therapies — reviewView study →}. A litre of tea delivers about 19% of a usual daily artemisinin dose ^{1Reference 1Räth et al. · 2004Clinical trialPharmacokinetic study of artemisinin after oral intake of a traditional preparation of Artemisia annua L. (annual wormwood) — clinical trialView study →}, and in trials many tea-treated infections returned ^{2,3Reference 2Mueller et al. · 2004RCTRandomised controlled trial of a traditional preparation of Artemisia annua L. in the treatment of malaria — randomised controlled trialView study →Reference 3Blanke et al. · 2008RCTHerba Artemisiae annuae tea compared to sulfadoxine-pyrimethamine in uncomplicated falciparum malaria — randomised double-blind clinical trialView study →}. The WHO does not support using the plant to prevent or treat malaria ^{24Reference 24World Health Organization · 2019The use of non-pharmaceutical forms of Artemisia — position statement and technical document (WHO/CDS/GMP/2019.14). https://www.who.int/publications/i/item/WHO-CDS-GMP-2019.14View study →}.

Retracted trials. A large trial claiming Artemisia tea outperformed artesunate-amodiaquine for malaria has been retracted ^{7Reference 7Munyangi et al. · 2020Retraction notice: Artemisia annua and Artemisia afra tea infusions vs. artesunate-amodiaquine in treating P. falciparum malariaView study →}, as has a trial claiming the tea cleared Schistosoma mansoni eggs faster than praziquantel ^{21Reference 21Munyangi et al. · 2020Clinical trialRetraction notice: Effect of Artemisia annua and Artemisia afra tea infusions on schistosomiasis in a large clinical trialView study →}.

Artesunate side effects. In the intravenous phase I trial, dose-limiting effects included neutropenic fever, a hypersensitivity reaction, liver-test abnormalities and nausea ^{9Reference 9Deeken et al. · 2018Clinical trialA phase I study of intravenous artesunate in patients with advanced solid tumour malignancies — clinical trialView study →}. Oral artesunate up to 200 mg a day caused occasional low blood counts and fatigue ^{10Reference 10von Hagens et al. · 2017Clinical trialPhase I study to define a well-tolerated dose of oral artesunate as add-on therapy in metastatic breast cancer (ARTIC M33/2) — clinical trialView study →}.

Allergy. A. annua pollen is a major cause of hay fever and asthma in northern China ^{32Reference 32Wang et al. · 2025In vitroImmunoproteomic analysis and identification of possible allergenic proteins in Artemisia annua pollen — in vitro / animalView study →}.

Interactions. No human drug-interaction study of the herb exists.