Yes. Sadly, grapefruit juice and actual grapefruit can interfere with the way your body deals with dozens of medications—even if you don’t drink the juice and take the pills at the same time. Just having grapefruit or grapefruit juice in your body can affect how well the medications work, and the effect can last up to a few days! In some cases, the combination can cause dangerous side effects ranging from drowsiness to serious problems with your heart and blood pressure.
We’re not talking about rare drugs either: The medications to watch out for include common blood pressure drugs, erectile dysfunction medications, anti-infections drugs, antihistamines, steroids, opioid painkillers, and even birth control pills.
Here is a list of some common medications affected by grapefruit juice:
A more complete list is available here, but the list of affected medications is always changing so it’s best to check with your doctor or pharmacist if you are a grapefruit-lover.
If you really want to know…
Grapefruit juice blocks enzymes responsible for breaking down medications in the body. The main enzyme affected is one called cytochrome p450 (or CYP450, for short). This can make the medication last longer in the blood and cause unwanted side effects.
Grapefruit can also interfere with medications in other ways: Sometimes it stops the medication from being converted in the body into a more “active” form. This can make the medication less effective.
Either way, grapefruit only has an effect on medications that you take as pills. It doesn’t affect intravenous medications.
How does this affect me?
This is where it gets complicated. The effect of mixing medications with grapefruit juice depends on so many factors—like which medications you take and how much grapefruit you consume—that we can’t give you a straight-up answer. That said, we’ll take a look at some common scenarios below.
Statins can be taken with moderate grapefruit intake: A daily 8 oz glass of grapefruit juice, or half a grapefruit, did not lower the effect of statins on cholesterol levels and did not cause worse side effects in this study.
Grapefruit juice can affect blood levels of sildenafil (Viagra), but this seems to vary from person to person. Mixing grapefruit juice with Viagra could (in theory) drop your blood pressure pretty significantly, so you should be careful and talk to your doctor before doing it—until you know how it affects you.
Grapefruit juice has a strange effect on some antihistamines, especially fexofenadine (Allegra), as it actually makes it less effective.
Clopidogrel (Plavix) normally prevents blood clots in those at high risk of having a stroke or heart attack, but grapefruit juice can make it less effective. If you are taking Plavix, you should definitely avoid grapefruit or grapefruit juice.
Grapefruit juice can lower the effectiveness of the levothyroxine (Synthroid) you take, meaning you may need to take a higher dose to get the same effect.
Some medications can reach toxic levels if taken with grapefruit juice. Taking a chance with these is not worth it, as the risks can be potentially serious. If you are on the following medications, you should change your morning drink or cocktail mixer to something other than grapefruit juice.
Grapefruit can cause new blood thinners like Eliquis and Xarelto to reach higher levels in the blood. A common side effect of this can be bleeding anywhere in the body, but this often happens first in your gut. If you are on these medications and drink grapefruit juice, you will need to keep an eye out for blood in your poop.
If you have ever had a transplant or take medications like Prograf, sirolimus (Rapamune), Afinitor, or cyclosporine (Neoral, Sandimmune) for another reason, you should avoid grapefruit juice as it can cause serious problems with your bone marrow and kidneys.
Some steroids like budesonide (Pulmicort) and methylprednisolone (Medrol) can reach higher blood levels if taken with grapefruit juice. This can dangerously raise your blood sugar levels and blood pressure, and cause other serious and sometimes long-lasting effects of too much steroids in the body.
Unfortunately, even a glass of the tart tangy nectar is enough to have a significant and lasting effect on the way your body handles your medication (anywhere from a few hours to a few days).
So, if you are a committed grapefruit-lover, we recommend talking to your doctor about your medications and how they might interact with grapefruit. You might be able to change to another medication that is not affected by grapefruit. Or you might have to switch allegiance to orange, apple, or pomegranate juice instead.