Why can't you eat grapefruit whilst taking Viagra?

Why can't you eat grapefruit whilst taking Viagra?

Fruit might seem like one of the safest foods, something you can never go wrong with. However, on the packaging for Viagra, and a lot of other medicines, you’ll find a warning saying you shouldn’t eat grapefruit whilst taking it. You expect to see certain precautions on medicines, like when best to take them, or other medicines they shouldn’t be mixed with. But it’s a common and intriguing fact that so many medicines, including Viagra, shouldn’t be taken whilst eating grapefruit or drinking its juice.

Sure, grapefruit juice can be a bit of an acquired taste, but how much damage can it do? Well, it turns out, a fair bit.

The good in grapefruit…

On its own, grapefruit juice is full of health benefits. Here are some of its juiciest good bits:

Grapefruit is high in anti-oxidants

Anti-oxidants have a range of health benefits, including reducing the risk of getting ill. Grapefruit are high in Vitamin C, beta-carotene (which is converted into Vitamin A), Lycopene (which slows the growth of some cancers) and flavanones (which reduce high blood pressure)

Grapefruit are really good for hydration

Grapefruit are about 88% water. Of course, the best way to get your two litres of water a day is to drink the stuff, but there’s no harm in upping your liquids with a grapefruit or two (unless you’re taking a medicine that doesn’t mix with grapefruit - then there is harm).

Grapefruit can help with weight loss

Of course, it doesn’t offer huge, life changing crash diet effects, but it does help. A 12 week Japanese study found a significant reduction in weight and blood glucose among those who ate half a grapefruit before meals and those who didn’t.

…and the bad.

But these good traits don’t outweigh the dangers by any stretch of the imagination. A study in 2002 conducted on 24 healthy, HIV negative men delved into what effect the fruit has on a dose of Viagra. The men drank a glass of grapefruit juice, then an hour later, drank another glass of grapefruit juice with a 50mg dose of Viagra. The experiment was repeated a week later with water instead of grapefruit juice.

Viagra absorption increased by 23% when taken with grapefruit juice.

The researchers discovered that absorption of Viagra increased by 23% when taken with grapefruit juice instead of water. Grapefruit juice was also found to delay the absorption of Viagra, which might lead to disappointment for some men, or even encourage them to take a bigger / further dose.

Grapefruit contains a substance which binds to an enzyme in your intestinal tract. This binding causes the medicine to be either more absorbed, less absorbed, or to pass through the body entirely, depending on what you take it with.

It is not yet known if this problem also affects other citrus fruits as there’s not enough research on the matter. However, you should always follow the instructions in your Patient Information Leaflet, and if that advises you stay away from grapefruit juice - or any other foods, drinks, or medicines - follow their advice.

This interference between grapefruit and medicines goes far beyond just Viagra. Regarding erectile dysfunction (ED) medicines, Cialis and Levitra are also thought to be affected by the fruit, but there are plenty of other non-ED drugs included too. These include statins, amphetamines, blood thinners such as Warfarin, and many others.

Sure, grapefruit can be good for your health - but it can be very, very bad, too.

Content Marketing Officer
Content Marketing Officer
Libby Mayfield

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