Benefits
Traditional European herbal tea for minor joint aches
The European Medicines Agency registers meadowsweet herb tea, powder and tincture as a traditional herbal medicine for minor joint aches. This status rests on at least 30 years of use, not on trials, and the agency's assessors found no clinical data supporting efficacy. The monograph limits this use to 4 weeks.
Inflammation markers in a three-herb drink study
In a 4-week randomized study, 20 healthy adults drank a berry-based beverage containing chamomile, meadowsweet and willow bark or the berry base alone. IL-1 beta fell about 22% on the herbal drink versus about 3% on the control, but no significant anti-inflammatory effect was found, and the study cannot separate meadowsweet from the other two herbs.
COX enzyme and cytokine activity in lab and rat studies
Lab and animal work only. A methanol extract of the aerial parts inhibited the COX-1 and COX-2 enzymes in a test tube (about 63% and 46% at 50 micrograms per ml) and reduced paw swelling in rats at 100 and 200 mg/kg. A water extract lowered IL-6 and TNF-alpha output from human immune cells grown in culture.
Pain sensitivity in a rat inflammation model
Animal work only. Freeze-dried meadowsweet flower tea given by mouth to rats at 100 to 300 mg/kg reduced sensitivity to pain in an inflamed paw in a dose-dependent way, with a half-maximal dose of about 165 mg/kg. It did not significantly reduce the swelling itself. No human pain study of meadowsweet alone exists.
Stomach lining in rodent studies
Animal work only. A flower decoction reduced stomach lesions caused by restraint, aspirin and other irritants in rats and mice and aided healing of alcohol-induced lesions, and freeze-dried flower tea given by mouth protected the rat stomach lining against alcohol. Yet the same decoction strengthened histamine's lesion-causing effect in guinea pigs, and EU assessors called the stomach findings contradictory.
Mechanism of action
Low salicylate content
Meadowsweet's salicylates are mostly salicylaldehyde and related glycosides that make up under 0.5% of the herb, compared with 0.5 to 10% in willow bark, according to the EU assessment. A cited pharmacology text describes water infusions as containing only trace salicylates. No study has measured salicylate levels in human blood after meadowsweet.
Flavonoids led by spiraeoside
The flowering herb contains about 3 to 4% flavonoids, mainly spiraeoside. Freeze-dried flower tea contained about 56 mg of spiraeoside per gram. In lab tests, spiraeoside scavenged free radicals and blocked formation of an inflammatory lipid (12(S)-HETE) in human platelets; at 50 mg/kg by mouth it also protected the rat stomach lining.
Ellagitannins and gut bacteria
Meadowsweet tannins such as rugosin D and tellimagrandin II blocked the histamine-making enzyme histidine decarboxylase in a test tube. When a water extract of the herb was incubated with human stool bacteria, the bacteria turned its tannins into urolithins, compounds that reduced TNF-alpha from cultured immune cells. Neither effect has been shown in people taking meadowsweet.
Clinical trials
Randomized, controlled 4-week study of a functional beverage combining three herbs in a berry extract base, with the berry extract alone as the control; the abstract does not state blinding or herb amounts. (Drummond et al. 2013, J Diet Suppl)
20 healthy adults, not selected for raised inflammation.
Serum IL-1 beta fell about 22% on the herbal drink and about 3% on the control, but the authors report no significant anti-inflammatory effect and call the evidence inconclusive. A subgroup analysis by baseline TNF-alpha showed lower IL-6 and some reported joint function improvement, without significance reported in the abstract. Meadowsweet was one of three herbs, so its own effect cannot be isolated.
In vitro enzyme and cell tests plus rat hot plate and carrageenan paw edema tests of methanol extracts of the aerial parts and the roots, with indomethacin as comparator. (Katanić et al. 2016, J Ethnopharmacol)
Rats given 100 or 200 mg/kg of extract; THP-1 human immune cells and isolated COX enzymes in vitro.
At 50 micrograms per ml the aerial-part extract inhibited COX-1 by about 63% and COX-2 by about 46%, roughly twice the root extract, but it cut COX-2 gene expression in cells by only about 10%. Both extracts lengthened hot plate latency (p<0.05) and the aerial-part extract reduced paw swelling at both doses. Animal and lab results only.
Animal study of freeze-dried flower infusions of meadowsweet and dropwort given by mouth in the carrageenan paw model, with an acute toxicity test in mice. (Samardžić et al. 2016, J Ethnopharmacol)
Rats with carrageenan-induced paw inflammation given 100 to 300 mg/kg by mouth; mice for toxicity.
Meadowsweet tea reduced pain hypersensitivity in a dose-dependent way (ED50 about 165 mg/kg) but did not significantly reduce paw swelling. Spiraeoside was the main compound at about 56 mg/g. In mice the estimated lethal dose was likely above 2,000 mg/kg, with animals observed for 14 days. Animal results only.
Antioxidant and anti-inflammatory lab assays and a rat alcohol-induced stomach injury model of freeze-dried flower infusions and isolated compounds. (Samardžić et al. 2018, J Ethnopharmacol)
Rats given freeze-dried meadowsweet or dropwort flower tea at 100 to 300 mg/kg by mouth, spiraeoside at 50 mg/kg or tellimagrandin II at 40 mg/kg (both compounds isolated from dropwort); human platelets and chemical assays in vitro.
The flower teas matched the positive control in two antioxidant assays and protected the rat stomach lining against alcohol, as did spiraeoside and tellimagrandin II. Spiraeoside blocked 12(S)-HETE formation in human platelets (IC50 about 4.7 micrograms per ml). The abstract gives no p values. Animal and lab results only.
Case report from the Italian herbal surveillance system of serious gastrointestinal bleeding after a multi-herb syrup. (Moro et al. 2011, Ann Ist Super Sanita)
A previously healthy 4-year-old boy given a multi-herb syrup containing Filipendula ulmaria and willow (Salix) for a mild cold with fever.
The boy developed shock from severe gastrointestinal bleeding; testing confirmed salicylates in the syrup, and the authors rated the link to the syrup as probable. He recovered after intensive care and the product was withdrawn from the Italian market. A single case with two salicylate herbs, so meadowsweet alone cannot be blamed.