Scientific Name: Red Clover
Other Names: Cow Clover, Meadow Clover, Purple Clover, Trefoil, Trifolium pratense, Wild Clover

Who is this for?

Uses

Because it contains chemicals called isoflavones, which belong to a larger class of plant chemicals known as phyto (plant-derived) estrogens, red clover is often taken to relieve symptoms of premenstrual syndrome (PMS). Isoflavones are similar in shape to the female hormone, estrogen. Therefore, they may attach to estrogen receptors throughout the body--particularly in the bladder, blood vessels, bones, and heart. For women with normal estrogen levels, red clover isoflavones may displace some natural estrogens, possibly preventing or relieving estrogen-related symptoms, such as breast pain, that are associated with PMS. This effect may also reduce the possibility of developing estrogen-dependent cancer of the endometrium (the lining of the uterus). In addition, results from a review of nearly 1,000 women suggest that red clover may interfere with an enzyme known to promote the progression of endometrial cancer. Red clover may also block enzymes thought to contribute to prostate cancer in men. However, red clover isoflavones may actually cause some types of existing breast tumors to grow faster.

In postmenopausal women, who generally have low blood levels of estrogen, red clover may act as hormone replacement. Taking it may relieve some menopause symptoms that are associated with low estrogen levels. Clinical studies have been inconclusive, however, in determining whether or not red clover isoflavones are effective at lessening the number or extent of hot flashes associated with menopause. Some study participants experienced various degrees of relief from hot flashes, while others observed no changes. Before red clover can be recommended, more studies are needed to determine whether it has any effects on cancer or the symptoms of menopause and PMS.

Taking red clover has been shown to help delay osteoporosis in women who have not yet reached menopause. The estrogen-like effect of red clover isoflavones may be involved, and red clover also may have a direct effect by preventing the breakdown of existing bone. However, this possible bone-strengthening effect has not been seen in men or post-menopausal women. Red clover has shown a definite limiting effect, however, in the development of benign prostate hyperplasia (BPH), which is a non-cancerous enlargement of the prostate gland. An enlarged prostate may cause men to experience a weak or interrupted urine stream, dribbling after urinating, or the urge to urinate even after voiding. For most men, BPH is a normal part of aging.

Red clover may also help to prevent heart disease in several ways. Although results from human studies are not definite, some show that taking red clover may lower blood levels of C-reactive protein, total cholesterol, triglycerides, and "bad" low-density lipoprotein (LDL) cholesterol--all factors that contribute to heart disease. At the same time, red clover may raise the levels of "good" high-density lipoprotein (HDL) cholesterol in the body. In addition, red clover may also promote an increase in the secretion of bile acid. Because cholesterol is a major component of bile acid, increased bile acid production usually means that more cholesterol is used and less cholesterol circulates in the body. Additionally, red clover contains small amounts of chemicals known as coumarins, which may help keep the blood from becoming thick and gummy. Therefore, the possibility of forming blood clots and arterial plaques may be reduced. Plaques are accumulations of blood cells, fats, and other substances that may build up in blood vessels, possibly reducing or blocking blood flow. Red clover may also help the arteries remain strong and flexible (a quality often called "arterial compliance"), which may also help to prevent some of the plaque deposits that may lead to a heart attack or a stroke.

Topical red clover preparations are used to treat various types of skin conditions. In folk medicine, fresh red clover flowers have been chopped or mashed and applied directly to skin wounds such as insect stings or snake bites. More recently, creams, lotions, or ointments containing red clover extract have been studied for treating psoriasis and other skin conditions. While all of these results need further documentation, animal studies have shown that red clover preparations may also protect skin against sunburn and damage caused by exposure to sunlight.

When should I be careful taking it?

Because red clover's estrogen-like chemicals may have caused abnormalities in babies born during studies of pregnant laboratory animals, taking red clover is not recommended for pregnant women.

Women with hormone-dependent conditions such as endometriosis, uterine fibroids, and cancers of the breast, ovaries, or uterus should not take red clover due to its possible estrogenic effects. Men with prostate cancer should also avoid taking red clover, unless a doctor recommends using it.

Precautions

Very little information is available on how red clover might affect an infant or a small child. Therefore, its oral use is not recommended while breastfeeding or during early childhood.

What side effects should I watch for?

Although no cases of red clover-related infertility have been reported in humans, some farm animals that ingested large amounts of red clover as feed became unable to reproduce.

Most of the side effects reported by humans who took red clover are mild and temporary. They include:

  • Headaches
  • Muscle aches
  • Nausea
  • Rash

Due to the coumarins it contains, red clover may decrease the ability of the blood to clot normally.

What interactions should I watch for?

Prescription Drugs

In studies and case reports, red clover has been shown to increase the time blood needs to clot. When it is taken with antiplatelet or anticoagulant drugs, the effect of the drug possibly may be increased, resulting in uncontrolled bleeding.

  • Antiplatelets include clopidogrel and Ticlid
  • Anticoagulants include heparin and warfarin

The isoflavones in red clover may act like estrogen in the body. When it is taken at the same time as estrogen replacement therapy or oral contraceptives, red clover may interfere with the way the body uses the estrogen. As a result, estrogens or oral contraceptives may not be as effective, some women may experience increased side effects, and the risk of an unintended pregnancy may be slightly higher.

Some evidence suggests that red clover may interfere with the anticancer effects of the drug tamoxifen. Therefore, red clover should not be taken at the same time as tamoxifen.

Because it is broken down by certain enzymes in the liver, red clover may possibly interfere with the use of prescription drugs that are processed by the same enzymes. Some of these drugs are:

  • Allergy drugs such as fexofenadine
  • Antifungal drugs such as itraconazole and ketoconazole
  • Cancer drugs such as etoposide, paclitaxel, vinblastine, or vincristine
  • Drugs for high cholesterol such as lovastatin
  • Oral contraceptives

Non-prescription Drugs

Red clover may decrease the ability of blood to clot after an injury. Aspirin can also delay clotting, so red clover should not be taken at the same time as aspirin.

Herbal Products

Theoretically, if red clover is used with other herbs that affect blood clotting, the risk of excessive bleeding may increase. Some of the most common herbal products that might inhibit blood clotting are:

  • Danshen
  • Devil's Claw
  • Eleuthero
  • Garlic
  • Ginger (in high amounts)
  • Ginkgo
  • Horse Chestnut
  • Panax Ginseng
  • Papain
  • Saw Palmetto

If red clover is taken at the same time as other herbs that also may affect estrogen levels, the effects of natural estrogen may be altered. Herbal products that may have estrogen-like effects include:

  • Alfalfa
  • Black Cohosh
  • Chaste Tree
  • Flaxseed
  • Hops
  • Kudzu
  • True Licorice
  • Soy

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how red clover interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.

Should I take it?

Familiar red clover plants commonly grow wild in meadows and other grassy areas of the Americas, Asia, Australia, and Europe. Since red clover has the ability to replace nitrogen in fields where nitrogen stores have been depleted by commercial crops, it may be cultivated in fields for a year or two between the planting of other crops. A plant that thrives in almost any climate, red clover is often used for animal grazing. Because it grows quickly, it may also be harvested for hay up to three times per summer.

Red clover plants are perennials, but they usually do not live more than a few years. Plants may be up to 2 feet tall depending on the species and growing conditions. They almost all have fuzzy stems that may be reddish in color. Their leaves are dark to medium green and they usually have a streak of white circling the middle. Characteristically, the oval-shaped leaves of red clover are clustered in sets of three. The rosy-pink to purple-red flowers that bloom from early summer to late fall are the parts used for medicine. They may be collected and dried at any time during the flowering period. Occasionally, red clover flowers are used fresh as a topical remedy for minor skin ailments such as insect bites.

Dosage and Administration

As oral dosage forms, red clover is most commonly available as capsules or extracts, which are concentrated liquid preparations usually made by soaking chopped or mashed plant parts in a liquid such as alcohol, and then straining out the solid parts. Although doses vary, a common recommendation for treating menopausal symptoms is 40 mg to 160 mg per day. Whether any doses of red clover actually relieve menopausal symptoms is questionable, however. For breast pain related to PMS, oral red clover doses of 40 mg to 80 mg per day appear to be effective for many women, but others find no benefit from any dose. One year-long study of men with prostate conditions used a dose of 60 mg per day. Individuals who decide to take a red clover product should follow package directions for the condition being treated.

A tea may be made by soaking one teaspoon to 2 teaspoons (about 3 flowers to 6 flowers) of dried red clover flowers in 8 ounces of boiling water for 10 minutes to 15 minutes. After the solid particles are removed, up to three cups may be consumed daily.

Dosage recommendations for topical red clover vary greatly. In general, it may be used as often as needed unless irritation develops at the site where it is applied. Red clover tea may be cooled and applied as a wash or a poultice to the skin. A poultice is usually a soft cloth that has been soaked in a medication, possibly heated, and applied to an injured area of skin surface. Commercially available creams, lotions, or ointments should contain at least 10% of red clover.


Summary

Isoflavones in red clover may help to reduce symptoms of pre-menstrual syndrome and menopause. Taking it may also decrease the risk of heart disease, high blood cholesterol, and some cancers. Orally, red clover may also lessen or delay osteoporosis. It may be used topically to treat skin conditions ranging from psoriasis to minor scrapes.

Risks

Pregnant and breast-feeding women and small children should avoid taking red clover due to uncertainty about its possible effects on a developing baby or a young child.

Side Effects

Eating large quantities of red clover has been associated with infertility in animals that graze on it. In humans, reported side effects may include headaches, muscle aches, nausea, or rash. Chemicals in red clover may make the blood less likely to clot normally.

Interactions

Red clover's estrogenic effects may interfere with estrogen replacement, oral contraceptives, or tamoxifen therapy. Due to its possible anticoagulant activity, red clover may possibly increase the effects of drugs and herbals that also thin the blood. It may also block the body's ability to use a number of drugs that are broken down by the same enzymes in the liver.

Last Revised July 31, 2008

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Last Revised July 31, 2008


Note: The above information is not intended to replace the advice of your physician, pharmacist, or other healthcare professional. It is not meant to indicate that the use of the product is safe, appropriate, or effective for you.

In general, herbal products are not subject to review or approval by the U.S. Food and Drug Administration (FDA). They are not required to be standardized, meaning that the amounts of active ingredients or contaminants they contain may vary between brands or between different batches of the same brand. Not all of the risks, side effects, or interactions associated with the use of herbal products are known because few reliable studies of their use in humans have been done.

This information is provided for your education only. Please share this information with your healthcare provider and be sure that you talk to your doctor and pharmacist about all the prescription and non-prescription medicines you take before you begin to use any herbal product.

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