Some science behind the scenes
Dicoumarol is related to coumarin. Coumarin of itself has no anticoagulant activity. Thus a normal coumarin containing plant generally has no ability to ‘thin the blood’. But there are a number of species of fungi that can transform coumarin into the natural anticoagulant dicoumarol. This can occur when plants are allowed to ‘ferment’. You may think this irrelevant, but I have seen recipes for smoking mixtures using the plants containing coumarin that require you to ferment the leaves and flowers first over quite a period of time. This ‘fermentation’ and chemical transformation takes place in the presence of naturally occurring formaldehyde. The dicoumarol so produced is classified as a mycotoxin.
To quote Meyer’s Side Effects of drugs
“Drugs with a proven antithrombotic action – whether by interference with the coagulation process, activation of the fibrinolytic system, or inhibition of platelet function – are known to induce a hemorragic diathesis, the severity of which increases with a given drug’s ability to interfere with the hemostatic mechanism. … For the indirectly acting anticoagulants of the coumarin type…….. The risk of bleeding is similar for all coumarin congeners, although a long acting variety such as phenprocoumon, which gives more stable hypocoagulability and hence significantly better persistence of the patient’s prothrombin time within the therapeutic range, tends to lead to a higher incidence of bleeding”
How it works
Smoking any mixture containing dicoumarol is a form of poisoning, but it may work initially via hypoxia not via cell death. If you thin the blood too much [overdose] you decrease the supply of oxygen to the brain, the system starts to shut down in a controlled manner, starting with memory and reason, reverting to core functions.