Saw palmetto is a plant. Its ripe fruit is used to make medicine. Saw palmetto is best known for its use in decreasing symptoms of an enlarged prostate. According to many research studies, it is effective for this use. Saw palmetto is used for treating certain types of prostate infections. It is also sometimes used, in combination with other herbs, to treat prostate cancer. Some people use saw palmetto for cold-and-flu. It is also used to increase urine flow (as a diuretic), to promote relaxation (as a sedative), and to enhance sexual drive.