Red Clover Tea: What Research Shows About the Tea, Safety and Cautions

Read this first: who should be careful

• Pregnancy and breastfeeding. NIH says red clover supplements may be unsafe during pregnancy or while breastfeeding. [1] Ask a clinician; see pregnancy and breastfeeding.
• Hormone-sensitive conditions. Red clover contains isoflavones, substances that NIH describes as structurally similar to estrogen. [1] A systematic review on breast cancer found evidence on red clover limited, with existing studies suggesting it may not have breast-cancer-promoting effects, and said better evidence is needed before high-dose isoflavones can be recommended for breast cancer patients. [2] If you have, or have had, a hormone-sensitive condition, ask your oncologist or clinician before using red clover in any form.
• Blood thinners. A pharmacy review of herbs and warfarin lists red clover among herbal products that may potentially increase bleeding risk or add to warfarin's effect, while noting that nearly all of that information comes from lab data, animal studies or single case reports. [3] Ask the prescriber or pharmacist; never change a prescribed medicine on your own. See how interactions work.
• Before surgery. Tell the surgical team about herbal teas (supplements before surgery).

What red clover tea is

Red clover tea is an infusion of red clover plant material (the plant part varies by product, so check the label), Trifolium pratense L., a legume in the pea family (Fabaceae). [4][1] NIH says it is native to Europe, central Asia and northern Africa. [1] The warfarin review lists sweet clover separately from red clover, so check the botanical name on the label (see herbal tea quality and labels). The plant profile and extract evidence are in Red Clover in Herbs & Botanicals.

Traditional use and what regulators concluded

Our sources give little detail on red-clover tea traditions, so we do not describe any here. NIH notes only that supplements containing red clover are promoted for women's health conditions. [1] No EU herbal committee (HMPC) summary for red clover was found in the sources we read, so no regulator conclusion is reported here.

What research found

Almost all trials tested isoflavone extracts or supplements, not tea. Labels used here: mixed, promising but limited, insufficient evidence.

Proper evidence not found for human trials of red clover tea: PubMed phrase searches for "red clover tea" in titles and abstracts returned no records, with or without a randomized-trial filter. [7] The sources we read do not say how many isoflavones a cup of tea contains. Do not assume tea works like the standardized extracts in these trials.

Safety details

• Length of use. NIH says red clover extracts have been used in clinical studies for as long as 2 years with apparent safety and appear well tolerated. [1] The Cochrane review found no indication of estrogen-like stimulation of the womb lining or vagina, or other adverse effects, in use up to two years. [5] These findings are for extracts.
• Vaginal bleeding after menopause. A scoping review of herbal products with assumed estrogen-like activity found that their use was associated with postmenopausal bleeding. [8] Tell your clinician about any bleeding after menopause; see Women's Health: When to Get Help.
• Other medicines, liver, kidney, allergy, children: Proper evidence not found in the sources we read for red clover tea.
• Quality. See quality testing and certifications for how product testing works in general.