The herb parsley, whose scientific name is Petroselinum crispum, has a reputation among herbalists as an emmenagogue, a substance that stimulates the uterus and may lead to uterine contractions. While parsley used as a food flavoring or garnish consumed in normal quantities has no side effects, parsley tea made from the plant leaves could possibly being on a menstrual period by causing uterine contractions. Parsley in large quantities has a history of use as an abortifacient. Do not drink parsley tea if you might be pregnant.
The components in parsley responsible for its emmenagogue effects include two volatile oils, apiol and myristicin. According to the Herbs2000 website, the content of each varies between different types of parsley; German parsley oil contains between 60 and 80 percent apiol, compared to French parsley oil, which contains less apiol but 50 to 60 percent myristicin. At one time, apiol was sold in capsules as an abortifacient, according to Drugs.com. Two other components of parsley, 6″-acetylapiin and petroside, have estrogenic effects similar to those of soybeans.
Evidence for the claim that parsley tea will start menstrual bleeding is lacking, although a Russian drug containing 85 percent parsley juice has been used as an aid for inducing labor. Other reports of its effectiveness are anecdotal; many herbalist and alternative medicine practitioners use this herb as an emmenagogue.
If you're pregnant, drinking parsley tea in large quantities could cause miscarriage. Since this herb has not undergone clinical testing for its uterine effects, it's not known how much tea you would need to drink to experience this effect. People who eat tabbouleh, a national dish in Lebanon containing large amounts of parsley, may consume as much as 50g of parsley in a meal, according to Drugs.com. If you are pregnant, avoid parsley except when used in small quantities as a cooking ingredient.
Wild parsley looks similar to three common poisonous plants: water hemlock, small hemlock and poison hemlock. Do not pick your own parsley to make into tea unless you're absolutely sure that you're picking parsley. Poisoning from these plants can cause nausea, vomiting, paralysis, dilated pupils, weakness and death. In large amounts, myristicin can have hallucinogenic effects.