This perennial herb in the poppy family is native to temperate and subarctic Europe and Asia.  It has an odd and unpleasant odor and a bitter and pungent taste. The word celandine is a corruption of the Greek word Chelidon, which translates as "a swallow".  
Although Greater Celandine is relatively unknown compared to many popular herbal remedies, the medicinal properties of C. majus were described by Dioscorides and Pliny the Elder way back in the first century AD. They valued it primarily for treating eye diseases and visual impairment, as well as toothache, ulcers, eczema and jaundice.
For the last two thousand years, Greater celandine has been used to treat a range of conditions including disorders of the liver. It is one of the best-known herbal folk remedies for jaundice and liver diseases, such as inflammation, spastic conditions, and gallstones. 
Greater Celandine is also used for various problems with the digestive tract including upset stomach, gastroenteritis, irritable bowel syndrome (IBS), constipation, loss of appetite, stomach cancer and intestinal polyps. It is an anti-parasitic, commonly known in Poland as “glistnik”  (roundworm herb).
Greater Celandine is used for inflammatory conditions such as gout, arthritis, rheumatism as well as fevers, spasmodic coughs, bronchitis, skin eruptions, ulcers and cancer.  
Other uses include detoxification, treating menstrual cramps, cough, pain, breast lumps, chest pain (angina), fluid retention (edema), arteriosclerosis, high blood pressure, asthma, gout, and osteoarthritis.
When smoked it is enjoyed for its light euphoric & sedating effect. It is often sold as Opi-8, due to its opiating effects and its botanical relationship to opium poppies (same plant family). 
Topically, Greater Celandine is applied directly to the skin for warts, rashes, eczema and scabies. The fresh root is also chewed to relieve toothache.