Chelidonium, also sometimes known as greater celandine and tetterwort, is a perennial plant. It is native to Europe and Asia, but is very common in North America. It belongs to the Papaveraceae family, which is commonly called the poppy family. Since ancient times, it has been used medicinally, and, in the modern age, is contained in some cancer-fighting drugs.

This herbaceous plant can reach up to four feet (1.22 m) tall, and have leaves with waved edges that look similar to those of the oak tree. Its blooms usually contain long, black seeds and are comprised of four petals, which can be various shades of yellow. It flowers fully during late spring, and this can sometimes last into early autumn. It drips a bright yellow or orange sap when cut or torn. Chelidonium is a very invasive plant and commonly runs rampant in wooded areas or large fields.

Although poisonous in large quantities, the plant can be used for medicinal purposes and has been for thousands of years. In fact, Pliny the Elder mentioned its healing properties in his Natural History in the 1st Century. It may have analgesic and sedative properties. The stem latex was once used, externally, for skin problems such as eczema, warts, and ringworm. When dried, chelidonium can be used as a tea to help gastrointestinal issues and gallstones. It can often be found under the name Celandine Tea in many health food or vitamin stores.

The alkaloids from the plant are currently used in Ukrain™, a drug used to treat cancer. Ukrain™ advocates claim the drug improves the health of people with cancers of the lungs, colon, breast, ovarian, pancreas, and kidneys. Some studies have shown small improvements in patients who have used Ukrain™, but further testing is needed for a true scientific analysis. Side effects of its use have been noted to include nausea, vomiting, pain in the affected area, and fever.

There are certain side effects that may occur when taking chelidonium. Some research has shown that it may cause hepatitis. It can also cause allergic reactions, like itching and rashes, in some people. In high doses, it can be toxic to humans, and, for this reason, the root of the plant should especially be avoided. The consumption of chelidonium has proven fatal to dogs and farm animals. Pregnant or nursing women should not use it.

Even though the plant is also known as tetterwort in Europe, it should not be confused with a plant known by the same name in North America. The North American tetterwort is more commonly known as bloodroot, and is also part of the poppy family, but an entirely different plant. Chelidonium is also often confused with lesser celadine, which is part of the buttercup family.