When the cat allergy I suffered as a teenager seemed to have reappeared at the end of last year, I went to the GP for advice.
I couldn't face the prospect of getting rid of my beloved moggy, so I wanted an allergy test to see if he really was the problem.
While I waited for an appointment for the test, my GP prescribed the non-drowsy antihistamine Fexofenadine hydrochloride and told me, in a casual way, to avoid grapefruit juice.
Bad reactions can be as serious as liver failure if juice interacts badly with cholesterol drugs, or dangerously low blood pressure if you're on drugs for high blood pressure
I started taking the drug and my symptoms disappeared. A month later, I was craving my favourite juice and had forgotten the GP's warning.
Within two days of drinking grapefruit juice, my heart was racing and, having previously suffered from arrhythmia (irregular heartbeat), I became anxious.
My doctor diagnosed the problem immediately as a bad interaction between grapefruit juice and the drug.
Who could imagine something that seems so healthy could harm you? Bad reactions to all fruit juices - but grapefruit juice in particular - are seen as so serious that you're meant to report them to the Medicines and Healthcare Products Regulatory Agency (MHRA).
The most serious case was when a healthy 29-year-old man was prescribed an antihistamine twice daily for a year to treat hay-fever.
He drank two glasses of grapefruit juice, took his drugs, became ill shortly afterwards and dropped dead after the interaction between the juice and the drug interfered with his heart rhythm.
Other bad reactions can be as serious as liver failure if grapefruit juice interacts badly with cholesterol drugs, or dangerously low blood pressure if you're on drugs for, ironically, high blood pressure.
Sometimes, with antibiotics for example, the drug will simply cease to work. There can be bad interactions with statins and some cancer drugs, too.
I usually give up wine in January, but, alarmed by what I'd been told, I haven't had grapefruit juice this year. How can fruit juice have such an effect? It seems some contain higher levels of the chemical naringin, a natural flavour, which causes too much of certain drugs to be absorbed into the bloodstream.
An enzyme in the gut that usually partially destroys the drug as it is absorbed is effectively knocked out by the naringin - transforming a safe medication into a potentially toxic overdose. It's not only naringin that's to blame; other chemicals called furanocoumarins which are found in juice can cause problems.
Grapefruit, with its high levels of both, is the main culprit, but orange and apple juices also contain damaging chemicals that can combine badly with drugs.
These include anti-cancer drugs such as etoposide, the beta blockers atenolol, celiprolol and talinolol, and the antibiotics ciprofloxacin, levo-floxacin and itraconazole.
The good news is that eating grapefruit segments is thought to be safe - it is the concentration of the chemicals in the juice that is responsible for adverse reactions.
The link between adverse drug reactions and fruit juice was made in 1991 by a Canadian pharmacologistyet some drug manufacturersare still giving patients insufficient warning about the risks, say experts.
'Every medicine that carries a risk of interacting with fruit juice should carry a warning in the patient information leaflet of every prescription. But this just isn't happening,' says Munir Pirmohamed, professor of pharmacology at Liverpool University and a specialist in adverse reactions.
Kelly-Ann Prime, a cardiac nurse with the British Heart Foundation, says: 'We know grapefruit juice and some statins react badly. A trial of one called Sinva showed that even small amounts of grapefruit juice increased the likelihood of sideeffects, including leg cramps and stomach problems.
There aren't enough warnings about the possible effects of grapefruit juice and statins, so patients need to be careful and aware.'
However, Professor Pirmohamed stresses that you should not suddenly stop taking prescribed medicine. 'We wouldn't want patients to take themselves off beneficial medication without good cause just because there's no mention of fruit juice in the leaflet - they should always talk to their doctor.'
So, if you are taking any medication, stay off the juice until you've seen your GP.
By LYNNE WALLIS
Source : http://www.dailymail.co.uk/health/article-1158671/How-healthy-fruit-juice-liver-failure-worse.html#ixzz3gdm3hrL9
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