"Do Not Take this Medication With Grapefruit Juice." Huh?

What will happen if I DO take my medication with grapefruit juice? Will I get sick? Will it make the medication work poorly? What is it about grapefruit juice that makes it any worse with this medication than, say, cranberry juice?

It’s certainly not a problem to avoid it, but I thought this was really strange. I mean, it doesn’t have a label warning not to take it with a martini.



Grapefruit juice has chemicals in it which inhibit the breakdown of certain medications, which can result in overdosing. See here.

I’m taking carbamazapine, and I’ve been told that grapefruit juice will reduce the efficacy of it, which I wouldn’t want. Of course, I don’t like grapefruit or their juice, so it’s not so great a risk. I do tend to check out the composition of any juice beverages, though, just in case.

http://www.webmd.com/food-recipes/tc/grapefruit-juice-and-medication-overview is a good overview.

Grapefruits affect the way that some medicines are absorbed and you end up with too much of the medication in your blood stream. My girlfriend takes anti-rejection meds due to a liver transplant and must avoid grapefruit.

Depends on the medication. Possible outcomes run the gamut from the drug will actually work better, to you’re taking an early dirt nap. I was reading something just a couple of days ago about a potentially fatal drug-grapefruit interaction, but I can’t remember what it is. It will probably come to me later. Is this a benzodiazepine we’re talking about?

You are presumably talking about statins. It’s just grapefruit. See here.

Holy crap - I see on preview that 5 others have responded more quickly.

It’s actually an anti-anxiety/anti-depressant medication called Buspar. Thanks for the information, everyone. I will certainly avoid it, that’s no big deal. And since I already have a gastric bypass taking some combination of stuff that would mess with absorption of medication in one way or another is a really bad idea for me so I appreciate the links!

The way the body processes drugs is actually incredibly complicated, and we’re just now really beginning to get a picture of some of the network of interactions involved.

Mixing grapefruit and a drug that is no longer alailable in the US caused me to have a dangerous cardiac dysrhythmia.

Is 6 the record for a simul-post?

There are also other foods that can change how a medicine works in your body. I always look at the manufacture’s site when prescribed a new medicine to see if their is an interaction with any foods.

I know a guy who swears that eating grapefruit or drinking grapefruit juice makes him develop cold sores (or makes them flare up, I suppose). Any truth to that?

Well, I can certainly see how it would irritate sores which had previously been painless (and hence, unnoticed). Grapefruit juice is a citrus juice, and hence fairly acidic.

so what about other fruits? The only pharmaceutical warnings I’ve ever heard are for grapefruit
Is grapefruit so much different from, say, lemon juice?

Grapefruit has a disproportionately high amount of bergamottin compared to all other fruits, except the bitter orange, which also has a nontrivial amount of bergamottin. Earl Grey tea, being flavored with bergamot oil, is of course to be avoided for the same reasons.

Not exactly on topic, but Jell-O warns you not to mix in pineapple – something about that particular fruit prevents the gelatin from setting.

Note that some grapefruit hybrids (e.g. the tangelo) do not contain furocoumarins (the class of chemicals including bergamottin), and thus don’t cause problems with statins. A good thing, too, as I have been known to eat as many as 5 tangelos a day.

Pineapple has a particularly strong protein-digesting enzyme. I assume it would chew up the gelatin.

Also, posters on message boards populated by recreational drug users frequently make the empirical observation that pink grapefruit juice “doesn’t work” to potentiate the effects of benzodiazepines. There may be something to this; the pink cultivars may contain less bergamottin than regular cultivars. They certainly taste different. Regular grapefruit juice has a subtle bitter/astringent aftertaste, which pink grapefruit juice doesn’t have. Is bergamotten the source of this flavor?