Caffeine adverse reactions

An article in the Canadian Adverse Reaction Newsletter published their reporting of adverse effects caused by products containing C. aurantium from January 1, 1998 to February 28, 2004 (46). The article lists 16 reports of synephrine associated with cardiovascular events including tachycardia, cardiac arrest, ventricular fibrillation, transient collapse, and blackout. In one case, bitter orange was the sole suspected culprit. In seven others the products also contained caffeine, and in eight cases the product contained both caffeine and ephedrine. Health Canada has issued an advisory stating that synephrine may have effects similar to ephedrine and caution should be used if taking it (47). 

In the six-year period from 1998 to 2004, Health Canada received 16 reports of cardiovascular adverse reactions associated with products containing bitter orange or synephrine. One of these products was reported to contain neither caffeine nor ephedrine, while the others contained one or both of these alkaloids (Jordan et al. 2004). 

Many medicinal plants have been used as natural supplements to reduce body weight. Supplements containing Ephedra, caffeine, and Bofutsushosan can cause minor adverse reactions, such as dry mouth, insomnia, nervousness, palpitation, headache, and loose stools [33 ]. 

In the absence of generally accepted, precise terminology, we must stress that the classification of adverse reactions shown in Fig. 1 depends upon our personal definitions of each of the terms. We define as usual (or toxic) reactions those reactions which occur in virtually all individuals ingesting a sufficient quantity of a particular substance. These include responses to toxins and the effects of pharmacological agents (caffeine in coffee, etc.). 

There may be some adverse effects due to excessive caffeine intake, such as restlessness, headaches, heart palpitations, heartburn, and insomnia. Some individuals may have a toxic reaction to it. Ingestion by pregnant women and nursing mothers may have adverse effects on fetuses and babies caffeine crosses the placenta and gets into breast milk. Caffeine has a wide margin of safety. A lethal dose for most people would be the amount of caffeine found in about one hundred cups of coffee. 

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