3. Blood Disorders. Blood disorders such as hemophilia and leukemia can cause unexplained bruising, often because your blood fails to clot properly. If you have severe and frequent unexplained bruising, it's a good idea to see a physician to rule out such disorders, especially if it seemed to come on suddenly.
Puffer fish contain the potent neurotoxin tetrodotoxin. TTX is thought to be synthesized by a bacterial or dinoflagellate species associated with the puffer fish. The toxin is concentrated in the liver, gonads, and skin. The level of toxicity is seasonal, and, in Japan, fugu is served only from October through March.
In some Strychnos plants a 9,10-dimethoxy derivative of strychnine, the alkaloid brucine, is also present. Brucine is not as poisonous as strychnine. Historic records indicate that preparations containing strychnine (presumably) had been used to kill dogs, cats, and birds in Europe as far back as 1640.