Red clover (Trifolium pratense) is an herb that belongs to the legume family, which also includes peas and beans. In herbal medicine, red clover is typically used to treat respiratory issues (such as asthma, whooping cough, and bronchitis), skin disorders (such as eczema and psoriasis), inflammatory conditions like arthritis, and women's health problems1 (such as menopausal and menstrual symptoms).
Red clover's brightly colored flowers contain many nutrients including calcium, chromium, magnesium, niacin, phosphorus, potassium, thiamine, and vitamin C. They're also a rich source of isoflavones. These are compounds that act as phytoestrogens—plant chemicals similar to the female hormone estrogen. Isoflavone extracts are touted as dietary supplements for high cholesterol and osteoporosis in addition to menopausal symptoms.
In alternative medicine, red clover is said to help with the following conditions. Note, however, that research hasn't shown that the herb is conclusively effective for these or any other health concerns.
A number of small studies have been done to see if red clover may help relieve the discomforts of menopause, especially hot flashes. Though you may hear some anecdotal support for this, there has been no conclusive evidence to back it up.
In fact, a research review conducted in 2013 notes that phytoestrogen treatments (including red clover) are not proven to effectively alleviate menopausal symptoms.
Research is ongoing as to whether isoflavones lower the loss of bone mineral density in postmenopausal women. Red clover is one source of supplements used in some studies.
A review done in 2016 concluded there may be some beneficial effects on bone health,3 while a 2017 review found that different formulations of red clover may be effective or ineffective.2
Preliminary research suggests that red clover may help reduce the risk of prostate cancer. In a 2009 study of prostate cancer cells, scientists found that treatment with red clover led to a decrease in the prostate-specific antigen (PSA), a protein found at elevated levels in men with prostate cancer.4
However, because of the estrogen-like effects of red clover, it could promote the growth of cancers that are boosted by estrogen, such as breast cancer and endometrial cancer.
A few clinical trials have looked at the effects of red clover on the development of risk factors for heart disease in postmenopausal women, with no strong evidence that it helps, reports Memorial Sloan Kettering Cancer Center.
Keep in mind that, due to the lack of long-term studies, it's too soon to recommend red clover for any condition. It's also important to note that self-treating a condition and avoiding or delaying standard care may have serious consequences.
Selection and Preparation
Red clover is available in a variety of preparations, including teas, tinctures, tablets, capsules, liquid extract, and extracts standardized to specific isoflavone contents. It's not always clear, however, that a product contains the promised isoflavone content.
One study found large differences between red clover products in this regard—differences that can significantly impact absorption rates, permeability, and metabolism of various isoflavones within these products.5
Sometimes red clover is the sole ingredient in products, but it's also often available mixed with other herbs. When using commercial products, follow the package instructions carefully.
Extracts of red clover isoflavones are different from the whole herb, and in fact, represent only a small, highly concentrated—and likely bioactive—part of the entire herb. As the researcher in the product study mentioned above notes, "the widespread use of self-administered isoflavones is somewhat unsettling since much remains to be proven including efficacy and possible side effects."
Making Red Clover Tea
You can also make tea from dried flower heads. Some proponents claim that to get the full benefit of red clover you need to use the whole flower, and not commercial red clover isoflavones, which many studies use.
To make a tea, use one to three teaspoons of dried red clover flowers for every cup of simmering (not boiling) water. Let steep for 15 minutes. Drink up to three cups of tea a day.
Possible Side Effects
Although red clover appears to be safe for short-term use, long-term or regular use may be linked to increased risk of cancer of the lining of the uterus.
Women who are pregnant or breastfeeding, along with anyone with hormone-sensitive cancers, which may be accelerated by phytoestrogens, should avoid red clover.
Red clover has blood-thinning abilities and can increase the effects of anticoagulant and antiplatelet drugs. Avoid taking it with blood thinners like Coumadin (warfarin) and stop taking it at least two weeks prior to surgery.
The herb may also interact with birth control pills due to the hormone-like actions of its isoflavones.
Red clover causes toxic effects when taken with methotrexate, a drug used to treat certain types of cancer and to control severe psoriasis or rheumatoid arthritis.
If you're considering using red clover, make sure to consult your physician first to avoid problematic drug-herb interactions.
Self-treatment should not exceed three to six months without the supervision of a healthcare professional.