# Cranberry (Vaccinium macrocarpon) **Vaccinium macrocarpon* Aiton; the small cranberry, *Vaccinium oxycoccus* L., is the marsh-wort or fen-berry of Folkard and the Ojibwe swamp berry bush; in pharmacy *Vaccinii macrocarpi fructus** **Known today as.** *Vaccinium macrocarpon*, an evergreen shrub whose red berries are, by the European Medicines Agency’s account, 88 per cent water. Massachusetts is one of the primary growing areas of the native plant. Its smaller relative *V. oxycoccus*, which the agency’s assessment report also counts among the cranberries, is the plant of the older European and Ojibwe sources below. Kind: Plant > **Caution.** Not with warfarin, whose effect cranberry may strengthen, nor with tacrolimus, whose blood levels fell in a kidney-transplant patient drinking cranberry juice. Not recommended for men, for pregnant women, or under eighteen, since their urinary symptoms need a doctor; anyone with kidney disease and recurrent infections needs medical supervision, and cranberry concentrate is high in oxalate, a risk for those with a history of urinary stones. See a doctor if fever, painful urination, spasms, or blood in the urine appear. Nausea, diarrhoea, indigestion, urticaria, and rash have been reported. LiverTox finds no link to liver injury and notes that cranberry may reduce the levels and effect of proton pump inhibitors and H2 blockers. ## What was it used for? A food first. The assessment report records that Native Americans ate wild cranberries for centuries in pemmican, crushed berries with fat and dried meat, though there is no recorded medicinal use among the tribes of Massachusetts; other peoples in Canada made a tea of the branches for pleurisy and poulticed wounds with the fruit, and First Nations people in Quebec applied crushed cranberries to sores. Seventeenth-century writers gave it for blood disorders, stomach ailments, fevers, and scurvy, and in 1905 the raw fruit was still a domestic poultice for erysipelas, swollen glands, ulcers, and tonsillitis. ## What does modern science say? The European Medicines Agency’s herbal committee accepts the fruit as a traditional herbal medicine, “exclusively based upon long-standing use,” to relieve the symptoms of mild recurrent lower urinary tract infections in women, such as burning or frequent urination, and to prevent recurrent uncomplicated lower urinary tract infections in women, in both cases after a doctor has excluded serious conditions (monograph of 2022). Its assessment report names the proanthocyanidins, chiefly chains of four or five epicatechin units, and the anthocyanin pigments among the constituents, with high levels of vitamin C. The Cochrane reviews of 2023 divide the two uses. For prevention, fifty studies in 8,857 participants support cranberry products in reducing symptomatic, culture-verified infections in women with recurrent infections, in children, and in people susceptible after medical interventions, but not in the elderly, in people with bladder-emptying problems, or in pregnancy. For treatment, the review found no randomised trials at all, and so “no good quality evidence to suggest that it is effective for the treatment of UTIs.” ## Pharmacognosy and toxicology - **proanthocyanidins**: chiefly chains of four or five epicatechin units - **anthocyanin**: the red pigments - **vitamin C**: at high levels **Mechanism.** Not established in the sources read for this entry. **Standing.** European Union herbal monograph (2022): traditional use, “exclusively based upon long-standing use,” for mild recurrent lower urinary tract infections in women and their prevention. Cochrane reviews (2023) support prevention in some groups and find no trials of treatment. ## What lore surrounds it? Folkard, writing of the small cranberry, says the Druids called the plant *Samolus* and gathered it with great ceremony, after a fast, without looking back while picking it, and with the left hand only, and that it was held especially good against the diseases of swine and cattle. New England folk practitioners, the assessment report adds, used boiled cranberries with seal oil to ease attacks of the gall bladder. ## What did the older authorities say? **Huron H. Smith, *Ethnobotany of the Ojibwe Indians* (1932).** Of the small cranberry, *Vaccinium oxycoccus*, which the Ojibwe called by a name meaning ‘swamp berry bush,’ Smith recorded “A tea for a person who is slightly ill with nausea,” and that white men had used its bitter, astringent leaves in diarrhoea and diabetes and for purifying the blood. ## Sources - Smith, H. H. (1932). *Ethnobotany of the Ojibwe Indians*, Cranberry (Vaccinium oxycoccus). Bulletin of the Public Museum of the City of Milwaukee 4. Project Gutenberg, 49527. - Folkard, R. (1884). *Plant Lore, Legends, and Lyrics*, “Cranberry.” Project Gutenberg, 44638. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Vaccinii macrocarpi fructus (Cranberry)*. EMA/HMPC/49135/2017, 23 November 2022. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Vaccinii macrocarpi fructus*. EMA/HMPC/517879/2016, 23 November 2022. - Williams G, et al. (2023). Cranberries for preventing urinary tract infections. *The Cochrane database of systematic reviews*. PMID 37947276. - Jepson RG, et al. (2023). Cranberries for treating urinary tract infections. *The Cochrane database of systematic reviews*. PMID 38096261. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Cranberry.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2023. NCBI Bookshelf. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Vaccinii macrocarpi fructus (Cranberry)*. EMA/HMPC/49135/2017, 23 November 2022. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Vaccinii macrocarpi fructus*. EMA/HMPC/517879/2016, 23 November 2022. - Williams G, et al. (2023). Cranberries for preventing urinary tract infections. *The Cochrane database of systematic reviews*. PMID 37947276. - Jepson RG, et al. (2023). Cranberries for treating urinary tract infections. *The Cochrane database of systematic reviews*. PMID 38096261. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Cranberry.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2023. NCBI Bookshelf. --- *Cranberry.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-16. The Thinking Press. https://thethinkingpress.org/materia-medica/cranberry Historical description, not medical advice.