Theobromine affects humans similarly to caffeine, but on a much smaller scale. Theobromine is mildly diuretic (increases urine production), is a mild stimulant, and relaxes the smooth muscles of the bronchi in the lungs. In the human body, theobromine levels are halved between 6-10 hours after consumption.

Theobromine has been used as a drug for its diuretic effect, particularly in cases where cardiac failure has resulted in an accumulation of body fluid. It has been administered with digitalis in order to relieve dilatation. Because of its ability to dilate blood vessels, theobromine also has been used to treat high blood pressure.

Cocoa and chocolate products may be toxic or lethal to dogs and other domestic animals such as horses because these animals metabolize theobromine more slowly than humans. The heart, central nervous system, and kidneys are affected. Early signs of theobromine poisoning in dogs include nausea and vomiting, restlessness, diarrhea, muscle tremors, and increased urination or incontinence. The treatment at this stage is to induce vomiting. Cardiac arrhythmias and seizures are symptoms of more advanced poisoning.

Different types of chocolate contain different amounts of theobromine. In general, theobromine levels are higher in dark chocolates (approximately 10 g/kg) than in milk chocolates (1-5 g/kg). Higher quality chocolate tends to contain more theobromine than lower quality chocolate. Cocoa beans naturally contain approximately 300-1200 mg/ounce theobromine (note how variable this is!).

Additional Reading

• Prescription-Strength Chocolate - From Science News Online, this article discusses the anandamide-like compounds in chocolate. These cannabinoids act similarly to THC in marijuana.
• Pet First Aid: Chocolate Poisoning in Dogs - Dr. Kevin Fitzgerald provides details about the effects of theobromine on dogs. His article describes the symptoms of theobromine poisoning and includes first aid information.
• Discovering the Sweet Mysteries of Chocolate - Ellen Kuwana reviews chocolate history and neurochemistry. She also provides a list of internet and printed references about chocolate.
• Howstuffworks 'Is chocolate poisonous to dogs?' - Marshall Brain not only answers the question, but also addresses chocolate toxicity to humans. Links to additional resources are also provided.
• Miscellaneous Chocolate Facts - This article separates chocolate facts from myths. Information is provided concerning chocolate and acne, allergies, dental caries, and weight control.
• Cacao - Botanical.com describes cacao and provides an overview of its history, constituents, and medicinal uses.

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