Parsley is a herb used in cooking and for making medicines. These are leaves, seeds, and roots which are used. Parsley proves to be effective in the treatment of kidney stones (nephrolithiasis), urinary tract infections (UTIs), gastrointestinal (GI) disorders, jaundice, constipation, intestinal gas (flatulence), colic, indigestion, diabetes, asthma, cough, fluid retention (edema), "tired blood" (anemia), osteoarthritis, high blood pressure, spleen conditions and prostate conditions. It can start menstrual flow, lead to an abortion in case of pregnancy, as a breath freshener, and as an aphrodisiac.
Sometimes parsley is applied directly to the skin to cure cracks, tumors, bruises, insect bites, parasites, lice, and to make hair grow faster. Parsley works due to special chemicals and their ability to improve digestion, stimulate the appetite, increase urine production, increase menstrual flow and reduce spasms.

Parsley is generally safe for adults when used as medicine for a short period of time. In some patients, parsley can lead to allergic reactions on the skin. Consuming too much parsley can lead to other side effects like anemia and problems with kidney or liver. Parsley seed oil which is usually applied to the skin can make the skin extremely sensitive to the sun rays. However, there is little information about the application of parsley leaf and root to the skin.
Breast-feeding and pregnancy are the reasons to avoid using parsley in medicinal amounts, but it is completely safe in food amounts. When taken by mouth in large amounts during pregnancy, parsley can lead to an abortion. In addition, there is supposition that consuming too much parsley during the first trimester of pregnancy raises the risk of birth defects. Little is known about the usage of parsley in medicinal amounts during breast-feeding, so women who take care of their infants should consume parsley in food amounts only.
There is some data that parsley can make the body hold onto salt which holds water in the body. This plant might also increase blood pressure.