Coumarin

Coumarin is a phytochemical with a vanilla like flavour. Coumarin is a oxygen heterocycle. Coumarin can occur either free or combined with the sugar glucose (coumarin glycoside). 1,2-Benzopyrone, 2H-1-Benzopyran-2-one Coumarin is found in several plants, including Tonka Beans, Cassia Cinnamon, lavender, licorice, strawberries, apricots, cherries, cinnamon, chamomile, Sweet Woodruff, Deer's Tongue and Sweet Clover.

Special Precautions of Coumarin

Coumarin can be toxic when used at high doses for a long period
Coumarin is moderately toxic to the liver and kidneys, with a "Median Lethal Dose" (LD50) of 275 mg/kg
Coumarin should not be taken while using anticoagulants. It should not be combined with warfarin or other blood-thinning medications, such as anticoagulants or antiplatelets like Coumadin, Plavix, heparin or aspirin or supplements that have the same effect or be used by people with bleeding disorders. It shouldn't be used two weeks before or after surgery. Avoid combination with other Herbal remedies that slow blood clotting like garlic, devil’s claw, papaya, ginger, Ginkgo Biloba, Red Clover and Asian or Siberian ginseng.
European health agencies have warned against consuming high amounts of cassia bark, one of the four species of cinnamon, because of its coumarin content
Coumarin is often found in artificial vanilla substitutes, despite having been banned as a food additive in numerous countries since the mid-20th century. Coumarin was banned as a food additive in the United States in 1954, largely because of hepatotoxicity results in rodents.
Coumarin is subject to restrictions on its use in perfumery as some people may become sensitised to it, however the evidence that coumarin can cause an allergic reaction in humans is disputed.