There is not enough research evidence to show that alfalfa treats kidney, bladder, and prostate conditions. Animal studies show that alfalfa helps with atherosclerosis (which can lead to heart disease) by reducing the hardening of the arteries, but effective research in humans still needs to be done. Animal studies also show that alfalfa decreases cholesterol and blood sugar levels; however, research in humans is needed to see if these effects are seen in people with high cholesterol and in people with diabetes.

More reliable evidence is needed to show that alfalfa is helpful for other uses, including stimulating appetite, helping with digestive problems, asthma, and arthritis.

Common side effects from alfalfa include: lupus-like effects (e.g., muscle pain, fatigue, skin rashes, fever, chest pain with deep breaths), mild stomach discomfort, diarrhea, gas, and skin redness or swelling. Rarely, alfalfa may cause a reduction in the number of blood cells and it may lower potassium levels.

Alfalfa can interact with some medications. It decreases the effectiveness of some birth control pills. If you are taking alfalfa along with birth control pills, use an extra method of birth control, such as a condom. Alfalfa can also interact with warfarin and other blood thinners, estrogen pills including hormone replacement therapy, medications that suppress the immune system (e.g., cyclosporine, corticosteroids), cholesterol-lowering medications (e.g., atorvastatin, simvastatin), and vitamin E.

Alfalfa makes you more sensitive to sunlight, so you should avoid taking it while taking other medications that also make you sensitive to sunlight (e.g., amitryptyline, ciprofloxacin, tetracycline). In addition, cover up (wear sun block, long sleeves, and a hat) if you are taking alfalfa and are in the sun.

You should avoid alfalfa if you are allergic to plants of the Fabaceae or Leguminosae families. People with grass allergies should also take caution.

You should also avoid alfalfa if you have a condition that is sensitive to hormones (e.g., breast cancer, endometriosis), if you have an autoimmune disease (e.g., multiple sclerosis, lupus, rheumatoid arthritis), or if you had a kidney transplant.

Women who are pregnant or breast-feeding should not use alfalfa. Consult your health care professional if you have any questions.

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.