ELI5. Grapefruit juice and the effects on mental health medication?

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To me it’s interesting that grapefruit juice is listed as a “no no” while taking antidepressants/anti-anxiety medication.

I’ve looked into it and I still don’t understand. Can someone explain why you aren’t supposed to mix them? I’m only asking because I like a good Ruby Grapefruit White Claw once and a while…

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13 Answers

Anonymous 0 Comments

It’s not just mental health medication. It’s tons of medications and not because the juice interacts directly with the drug, it inactivates enzymes that metabolize many things which can alter the duration or the dosage you are taking.

Anonymous 0 Comments

Chemicals in the grapefruit inactivate enzymes in the liver that process drug molecules. This can mean that too much of a drug enters your system in the first place or that it’s broken down more slowly than expecting, allowing a toxic dose to build up, or (the strangest case) some drugs are given in a form that require those liver enzymes to turn it into the active drug, meaning you’d get *too low a dose* of such medicines as a result.

I made a video about this! [Three ways grapefruit can kill you](https://www.youtube.com/watch?v=QJdU5VXo85M). 🙂

Anonymous 0 Comments

When I was prescribed Lipitor to help with my cholesterol levels I was told by my Dr to specifically avoid grapefruit juice.

I asked why and the response was it could trigger a higher than normal experience with the side effects of the drug.

That was enough for me. I missed my once in a while grapefruit but was happy to minimise any potential side effect risks.

Anonymous 0 Comments

I used to regularly take kratom and it just wasn’t the same without grapefruit or cranberry juice.

Anonymous 0 Comments

Your liver is responsible for chemically neutralizing poisons, including some medicines. It does that using specific enzymes for specific types of poisons. If you eat something that needs to be destroyed by a particular liver enzyme, it’ll share that enzyme with anything else you’ve eaten that also needs it, which causes both poisons to break down slower than they would if you’d only eaten one.

Grapefruits contain small amounts of mildly toxic chemicals called furanocoumarins. The amounts are small enough and the toxicity is mild enough that your liver can neutralize them before they cause any problems. But the liver enzyme that neutralizes grapefruit furanocoumarins is shared with some medicines. That means eating grapefruit causes those medicines to build up in your body instead of being destroyed over time. You end up with too much medicine in your body, just like if you’d overdosed.

If you’ve ever been told not to mix Tylenol and alcohol, that’s another pair that shares a liver enzyme. Drinking alcohol can cause you to get Tylenol poisoning without taking too many Tylenol pills.

Anonymous 0 Comments

Its also a very strange collection of medications, not all antidepressants or anti-anxiety medications but includes some medications for blood pressure, cholesterol, etc

Here is an article from Harvard that explains the effect AND lists meds that are or are not impacted. https://www.health.harvard.edu/staying-healthy/grapefruit-and-medication-a-cautionary-note

Anonymous 0 Comments

The grapefruit interaction was found when they were testing a combinaiton of a blood pressure drug and alcohol, and were using the grapefruit juice to mask the taste of alcohol, so they could have a placebo group.

The grapefruit juice increases the rate that youi absorb some drugs, which can cause similar effects to a higher dose of the drug

You can probably still have the white claws, there is very little grapefruit juice in them

Anonymous 0 Comments

Grapefruits (and a few related fruits as well) have an enzyme in it that changes how the digestive system absorbs certain chemicals. Some, it decreases how much chemical is absorbed; the (potentially) life saving drug isn’t absorbed enough to be useful. Others, it helps the body absorb the chemical *too well*; a normal dose suddenly becomes an overdose, which can be devastating. It depends on how the drug works and how the body is expected to absorb the chemicals in it.

If you want further reading there’s an extensive [wiki page](https://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_interactions) on the effect. I recommend it for more details, chemical names, and some of the related fruits that can also be a problem.

Anonymous 0 Comments

Medications are dosed assuming a certain percentage of them flat out won’t work – your body will process some of them and kick them out prior to them entering the bloodstream. One of the ways it does this is with the use of certain enzymes. The problem is that grapefruit juice interacts with the enzyme, and if its tying up all the enzyme when you take a pill, it can’t intercept part of the medicine. Since the dosage is made assuming the enzyme will block some of it and it no longer does, you end up with a far higher dose than intended. For mental health medication, this is a REALLY big problem – these drugs tend to have a narrow effective range vs. the range where they start having too many negative effects, and even if they don’t, your doctor needs to know how much you are actually getting so they can adjust your dosage.

Weirdly enough, there are some other drugs where grapefruit juice has the *opposite* effect for other reasons. In these cases, the grapefruit juice is affecting proteins which transport the drug into your bloodstream. Disrupt those, and you end up with *not enough* drug.

Grapefruit juice is not the only food/drink that can cause these problems, but it’s certainly one of the more notable ones.

Anonymous 0 Comments

Your liver has an enzyme called cytochrome P450 enzyme 3A4. This enzyme is important in modifying and breaking down a lot of chemicals and is taken into account when determining dosage of some drugs.

Graprefruit juice has a chemical in it that inactivates this enzyme.

So, if you drink grapefruit juice, you might overdose or take the wrong dose of some drugs because the dose is planned with the enzyme activity taken into account.

So, you have to avoid grapefruit juice when on some specific drugs.