500px Some fruit juices and fruits can interact with numerous<unk> s, in many cases causing adverse effects. The effect was first discovered accidentally, when a test of<unk><unk>  with alcohol used<unk>  juice to hide the taste of the ethanol. The effect is most studied with<unk>  and<unk>  juice, but similar effects have been observed with certain other citrus fruits. A 2005 medical review advised patients to avoid all citrus juices until further research clarifies the risks. It was reported in 2008 that similar effects had been observed with apple juice. One whole<unk> , or a small glass () of<unk>  juice, can cause<unk>  overdose toxicity. Fruit consumed three days before the medicine can still have an effect. The relative risks of different types of citrus fruit have not been systematically studied. Affected<unk> s typically have an auxiliary label saying "Do not take with<unk> " on the container, and the<unk> is elaborated upon in the package insert. People are also advised to ask their physician or pharmacist about<unk><unk> . The effects are caused by furanocoumarins (and, to a lesser extent, flavonoids). These chemicals inhibit key<unk>  metabolizing enzymes, such as cytochrome P450 3A4 (CYP3A4). CYP3A4 is a metabolizing enzyme for almost 50% of<unk> s, and is found in the liver and small intestinal epithelial cells. As a result, many<unk> s are affected. Inhibition of enzymes can have two different effects, depending on whether the<unk>  is either #metabolized by the enzyme to an inactive metabolite, or #activated by the enzyme to an active metabolite. In the first instance, inhibition of<unk> -metabolizing enzymes results in elevated concentrations of an active<unk>  in the body, which may cause adverse effects. Conversely, if the medication is a prodrug, it needs to be metabolised to be converted to the active<unk> . Compromising its metabolism lowers concentrations of the active<unk> , reducing its therapeutic effect, and risking therapeutic failure. Low<unk>  concentrations can also be caused when the fruit suppresses<unk>  absorption from the intestine.
Grapefruit–drug interactions
Pesticide poisoning
Allergic shiner
NSAID hypersensitivity reactions
Amnesic shellfish poisoning
Non-freezing cold injury
Chinese alchemical elixir poisoning
Paralytic shellfish poisoning