Background

Red clover (Trifolium pratense) is a flowering plant that grows 15-40 cm high. It's eaten as a legume and used in supplements marketed for female health.

Red clover contains chemicals called phytoestrogens that are similar to the hormone estrogen. It grows in many areas, including Europe, central Asia, and northern Africa.

People commonly use red clover for symptoms of menopause, weak and brittle bones, breast pain, male-pattern baldness, and many other conditions, but there is no good scientific evidence to support any of these uses.

Don't confuse red clover with sweet clover. They are different plants.

Safety Safety definitions

When taken by mouth: Red clover is commonly consumed in foods. Red clover products contain chemicals called isoflavones. It is possibly safe to take red clover in doses that provide up to 80 mg of isoflavones daily for up to 2 years. It's usually well-tolerated, but might cause muscle aches, nausea, and vaginal bleeding (spotting) in some people.

When applied to the skin: Red clover is possibly safe when used for up to 4 weeks.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Red clover is commonly consumed in foods. But it's possibly unsafe when used in medicinal amounts. Red clover might act like estrogen, which could affect hormone balances during pregnancy or breast-feeding. Don't use it.

Hormone-sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Red clover might act like estrogen. If you have any condition that might be made worse by estrogen, don't use red clover.

Effectiveness

Dosing & administration

Red clover has most often been used by adults in doses of 40-80 mg by mouth daily for up to one year. Keep in mind that doses vary depending on the specific product used. Speak with a healthcare provider to find out what product and dose might be best for a specific condition.

Interactions with pharmaceuticals

Caffeine

Interaction Rating=Minor Be watchful with this combination.

Red clover contains the chemical genistein. Genistein might slow down how quickly the body gets rid of caffeine. But red clover doesn't seem to have enough of this ingredient to actually increase the effects of caffeine.

Estrogens

Interaction Rating=Moderate Be cautious with this combination.

Large amounts of red clover might have some of the same effects as estrogen. Taking red clover along with estrogen might decrease the effects of estrogen.

Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)

Interaction Rating=Minor Be watchful with this combination.

Some medications are changed and broken down by the liver. Red clover might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C19 (CYP2C19) substrates)

Interaction Rating=Minor Be watchful with this combination.

Some medications are changed and broken down by the liver. Red clover might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Interaction Rating=Minor Be watchful with this combination.

Some medications are changed and broken down by the liver. Red clover might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Interaction Rating=Minor Be watchful with this combination.

Some medications are changed and broken down by the liver. Red clover might change how quickly the liver breaks down these medications. This could change the effects and side effects of these medications.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Minor Be watchful with this combination.

Red clover might slow blood clotting. Taking red clover along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

Methotrexate (Trexall, others)

Interaction Rating=Moderate Be cautious with this combination.

Red clover might increase levels of methotrexate in the body. This might increase side effects from methotrexate such as vomiting and stomach pain.

Tamoxifen (Nolvadex)

Interaction Rating=Moderate Be cautious with this combination.

Red clover might decrease the effects of tamoxifen. Do not take red clover if you are taking tamoxifen.

Interactions with herbs & supplements

Caffeine-containing herbs and supplements: Red clover contains genistein. Genistein might decrease how quickly the body breaks down caffeine. But research suggests that red clover doesn't contain enough genistein to change the levels or side effects of caffeine.
Herbs and supplements that might slow blood clotting: Red clover might slow blood clotting and increase the risk of bleeding. Taking it with other supplements with similar effects might increase the risk of bleeding in some people. Examples of supplements with this effect include garlic, ginger, ginkgo, nattokinase, and Panax ginseng.

Interactions with foods

There are no known interactions with foods.