Corn Silk Tea and Barley Tea: What Is Known
What is known about corn silk tea and barley tea (mugicha): thin human research, gluten in barley, diuretic and potassium questions for corn silk, and when to ask a clinician.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read herbal tea and extract safety before you use anything on this page.
Read this first: who should be careful
- Gluten and barley tea. NHS describes gluten as a dietary protein found in three cereals: wheat, barley and rye, and coeliac disease as a condition in which the immune system attacks the body's own tissues when gluten is eaten. [1] Barley tea is made from barley. The sources we read do not say whether, or how much, gluten reaches the drink, so people with coeliac disease or gluten-related conditions should ask their clinician or dietitian before drinking it.
- Blood pressure medicines and corn silk. The corn silk trials we read tested corn silk tea added to blood pressure medicines, not instead of them. [2] Never stop or change a prescribed medicine; ask the prescriber or pharmacist. See how interactions work.
- Kidney disease. Corn silk is traditionally used for urinary complaints and is described as a diuretic [3]. If you have kidney disease or take water pills, ask your clinician first (kidney disease and supplements).
Corn silk tea
What it is. Corn silk tea is an infusion of the silky threads (stigmas) of Zea mays L., the maize plant, a grass in the Poaceae family. [4][5] It is a herbal tea (tisane), not a tea-plant tea; see Tisane vs Tea.Traditional use. A 2012 review says corn silk is an herb used traditionally by the Chinese and Native Americans to treat many diseases, and that teas and supplements are used for urinary-related problems. [3]
Regulatory view. The EU herbal committee's page for corn silk (Maydis stigma) shows the work as still draft: the European Medicines Agency says it is currently developing this information, with status "Draft under discussion" and a therapeutic area of urinary tract and genital disorders. [5] We found no finished EU conclusion to report.
What research found. Labels used: insufficient evidence, preclinical (cells or animals).
| Question | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| High blood pressure | A review of 5 randomized trials (567 participants) found that, because of poor method quality in most trials, limited evidence showed corn silk tea plus blood pressure drugs might lower blood pressure more than the drugs alone. [2] | Insufficient evidence (poor-quality trials, add-on design) | People with hypertension already on medicines |
| Side effects | The review found no evidence that adding corn silk tea led to fewer adverse events than the drugs alone. [2] | Insufficient evidence | Same trials |
| Diuretic and potassium | In water-loaded rats, a corn silk water extract was diuretic at 500 mg/kg and changed potassium excretion. [6] | Preclinical (animals) | Rats, aqueous extract, not people |
| Fluid loss in people | Proper evidence not found in the sources we read |
Because the rat study looked at potassium excretion, people on diuretics, heart medicines or with kidney disease should ask a pharmacist; no human source we read measured this for the tea. See Diuretic Teas and Fluid Balance.
Barley tea (mugicha)
What it is. Barley tea, called mugicha in Japanese, is an infusion of roasted barley grains. [7] Barley is Hordeum vulgare L., a grass in the Poaceae family. [4] It is a roasted-grain drink, not a tea-plant tea, and it is a different thing from barley as a food; see Barley in Functional Foods.Traditional use. One trial abstract describes roasted barley extract as a traditional Japanese beverage. [8] Our sources do not give more detail on its history.
What research found. Labels used: promising but limited, proper evidence not found.
| Question | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Skin temperature in cool rooms | In a randomized, double-blind crossover study of 15 people, skin blood flow and skin temperature fell less after a roasted barley extract drink than after placebo while in an air-conditioned room. [9] A second crossover study reported higher foot skin temperature with the drink than placebo over 100 minutes. [8] | Promising but limited (small studies, measured skin temperature, not symptoms or health outcomes) | Adults; a beverage extract with a specific compound, which may differ from tea made at home; authors of one study list a beverage company as their affiliation |
| Blood sugar, weight, digestion, other uses | Proper evidence not found. Our phrase searches of PubMed found 28 records for "barley tea" and 11 for "mugicha", of which the human trials we read were the skin-temperature studies above. [10] |
Caffeine. The 2018 trial's authors call the drink non-caffeinated. [9] Check the label, and see Caffeine in Herbal Teas.
Acrylamide in the roasting. A food-chemistry study found that acrylamide, a substance formed when grain is roasted, is highly water-soluble and was easily extracted into mugicha from milled roasted barley in tea bags; in loose grain, the amount in the drink increased with longer simmering and steeping. [7] Darker-roasted grain contained less acrylamide, and the authors framed the work as helping lower acrylamide intake from mugicha. [7] The abstract does not say what level is harmful, and we do not draw a health conclusion from it.
Frequently asked questions
Is barley tea gluten-free?
It is made from barley, and NHS lists barley among the three cereals that contain gluten. [1] The sources we read do not say how much gluten gets into the drink. Ask your clinician or dietitian if you have coeliac disease.
Does corn silk tea lower blood pressure?
Proper evidence not found that it does on its own. The only trials we read tested it added to blood pressure drugs and were mostly poor quality. [2]
Is corn silk tea a diuretic?
It is described that way traditionally [3], and a rat study found a diuretic effect of a water extract at a high dose. [6] We found no human study measuring this for the tea.
Does barley tea warm the body?
Two small crossover studies of a roasted barley beverage reported smaller drops in skin temperature in cool rooms. [9][8] That is a skin measurement, not a health benefit, and the products may differ from home-brewed tea.
Does barley tea contain caffeine?
The trial authors describe roasted barley drink as non-caffeinated. [9] Check the label.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety summary
- Medicines: Proper evidence not found in the sources we read for barley tea; for corn silk see the blood pressure note above.
- Pregnancy, breastfeeding, children: Proper evidence not found in the sources we read for either tea. Ask a clinician (pregnancy and breastfeeding).
- Quality: Contamination and labeling vary between products; see herbal tea quality and labels.
References
- NHS (UK). Coeliac disease: overview. Read 2026-10-23.
- Shi S, et al. Corn silk tea for hypertension: a systematic review and meta-analysis of randomized controlled trials. Evid Based Complement Alternat Med 2019. Read 2026-10-23 (abstract).
- Hasanudin K, Hashim P, Mustafa S. Corn silk (Stigma maydis) in healthcare: a phytochemical and pharmacological review. Molecules 2012. Read 2026-10-23 (abstract).
- GBIF Secretariat. GBIF Backbone Taxonomy, species match for Trifolium pratense L. (Fabaceae), Silybum marianum (L.) Gaertn. (Asteraceae), Echinacea purpurea (L.) Moench and Echinacea angustifolia DC. (Asteraceae), Rubus idaeus L. (Rosaceae), Zea mays L. and Hordeum vulgare L. (Poaceae), Jasminum sambac (L.) Aiton (Oleaceae), Chrysanthemum x morifolium Ramat. ex Hemsl. (Asteraceae). All returned as accepted names by the API on 2026-10-23.
- European Medicines Agency, HMPC. Maydis stigma (corn silk): herbal medicinal product, status page. Read 2026-10-23.
- Velazquez DV, et al. Zea mays L. extracts modify glomerular function and potassium urinary excretion in conscious rats. Phytomedicine 2005. Read 2026-10-23 (abstract).
- Mizukami Y, Yoshida M, Ono H. Acrylamide elution from roasted barley grains into mugicha and its formation during roasting. Food Addit Contam Part A 2016. Read 2026-10-23 (abstract).
- Ashigai H, et al. Roasted barley extract (mugicha) containing cyclo(D-Phe-L-Pro) prevents a decrease in skin temperature in cold conditions: a randomized, double-blind, placebo-controlled, crossover study. J Nutr Sci Vitaminol 2019. Read 2026-10-23 (abstract).
- Ashigai H, et al. Roasted barley extract (mugi-cha) containing cyclo(D-Phe-L-Pro) prevents lowering of the cutaneous blood flow and skin temperature under air conditioning: a randomized, double-blind, placebo-controlled, crossover study. J Agric Food Chem 2018. Read 2026-10-23 (abstract).
- National Library of Medicine. PubMed search records, E-utilities esearch, phrase searches in title/abstract run 2026-10-23, with and without a randomized-controlled-trial filter: "red clover tea" (0 records), "milk thistle tea" (0), "echinacea tea" (0), "raspberry leaf tea" (9; 2 with the trial filter), "barley tea" (28; 3 with the trial filter), "mugicha" (11; 3), "chrysanthemum tea" (40; 0), "jasmine tea" (79; 0), "corn silk tea" (6; 0).