There is interest in using alfalfa for a number of purposes, but there isn’t enough reliable information to say whether it might be helpful.

When taken by mouth: Alfalfa leaves are possibly safe when used short-term. But taking alfalfa in high doses or long-term is likely unsafe. Long-term use might cause reactions similar to the autoimmune disease called lupus in some people.

Special precautions & warnings:

Pregnancy and breast-feeding: Using alfalfa in amounts larger than what is commonly found in food is possibly unsafe during pregnancy and breast-feeding. Alfalfa might act like estrogen in the body.

“Auto-immune diseases” such as multiple sclerosis (MS), lupus (systemic lupus erythematosus, SLE), rheumatoid arthritis (RA), or other conditions: Alfalfa might cause the immune system to become more active, and this could increase the symptoms of auto-immune diseases. If you have an auto-immune condition, avoid using alfalfa until more is known.

Hormone-sensitive condition such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Alfalfa might have some of the same effects as estrogen. If you have any condition that is sensitive to estrogen, don’t use alfalfa.

Major

Do not take this combination.

Warfarin (Coumadin)

Alfalfa contains large amounts of vitamin K. Vitamin K is used by the body to help blood clot. By helping the blood clot, alfalfa might decrease the effects of warfarin. Be sure to have your blood checked regularly. The dose of your warfarin might need to be changed.

Moderate

Be cautious with this combination.

Birth control pills (Contraceptive drugs)

Large amounts of alfalfa might have some of the same effects as estrogen. Taking alfalfa along with birth control pills might decrease the effects of birth control pills. If you take birth control pills along with alfalfa, use an additional form of birth control such as a condom.

Estrogens

Large amounts of alfalfa might have some of the same effects as estrogen. Taking alfalfa along with estrogen might change the effects of estrogen.

Medications for diabetes (Antidiabetes drugs)

Alfalfa might lower blood sugar levels. Taking alfalfa along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.

Medications that decrease the immune system (Immunosuppressants)

Alfalfa can increase the activity of the immune system. Some medications, such as those used after a transplant, decrease the activity of the immune system. Taking alfalfa along with these medications might decrease the effects of these medications.

Medications that increase sensitivity to sunlight (Photosensitizing drugs)

Some medications might make the skin more sensitive to sunlight. Alfalfa might also make the skin more sensitive to sunlight. Using these products together might increase the risk of sunburn, blistering, or rashes when the skin is exposed to sunlight. Be sure to wear sunblock and protective clothing when spending time in the sun.

Herbs and supplements that might lower blood sugar

Alfalfa might lower blood sugar. Taking it with other supplements with similar effects might lower blood sugar too much. Examples of supplements with this effect include aloe, bitter melon, cassia cinnamon, chromium, and prickly pear cactus.

Herbs that might increase sensitivity to sunlight

Alfalfa might make the skin more sensitive to sunlight. Using it with other products that also make the skin more sensitive to the sun might increase the risk for sunburn and other side effects. Examples of supplements with this effect include bishop’s weed, chlorophyll, khella, and St. John’s wort.

Iron

Taking alfalfa might reduce the amount of iron absorbed by the body.

Vitamin E

Taking alfalfa might reduce the amount of vitamin E absorbed by the body.

There are no known interactions with foods.

There isn’t enough reliable information to know what an appropriate dose of alfalfa might be. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult a healthcare professional before using.