Published on September 27, 2022 at 13:21 / Updated on October 27, 2022 at 15:49

If your pharmacist tells you to avoid grapefruit and grapefruit juice with your cholesterol medication, it's important to follow their instructions. Your pharmacist is your drug specialist; if they warn you about combining your medication with grapefruit, there is a reason. Indeed, as you will see in the following article, several factors can modify the effect of medications. These are what we call drug interactions.

What is a drug interaction?

A drug interaction occurs when the combined administration of several drugs or foods alters the effects of at least one drug. A drug interaction can lead to treatment failure, increased or decreased therapeutic effects, adverse effects, toxic effects, etc. In some cases, an interaction may be beneficial and even desired, as in the case of certain HIV antiviral treatments.

Le pamplemousse et son jus

As mentioned earlier, grapefruit and its juice can interfere with some medications. It is at the liver level that this fruit can have an impact on several drugs. This interaction can lead to a substantial increase in the concentrations of the drugs involved, which can cause adverse reactions that can be very serious. Seville oranges, limes, pummelos and tangelos can have a similar effect, but other citrus fruits (limes, lemons, oranges and tangerines) are considered safe.


We often hear that moderation is best when it comes to alcohol. When combining it with medication, abstinence from alcohol is often the best solution. Whether it's increased drowsiness, stomach irritation or increased side effects, alcohol rarely works well with medication. If your pharmacist tells you to avoid alcohol with your medication, listen to them!

Calcium and other minerals

Calcium, found in dairy products, and many other minerals, such as magnesium, can bind to certain medications and can decrease or cancel their effect. Often, simply spacing the medication from the minerals can be enough to avoid the impact of this drug interaction. Your pharmacist can tell you what to do.

La vitamine K

We rarely hear about vitamin K. However, it can significantly impact a patient taking certain anticoagulants. This vitamin, which is found in large quantities in broccoli, cabbage and organ meats, can reduce the effect of warfarin, a frequently prescribed anticoagulant. In doing so, a patient who consumes a large amount of vitamin K may be at risk for blood clots. Usually, consuming foods rich in vitamin K is not prohibited, but consistency is required to adjust the medication accordingly.


Cigarette smoke can cause many interactions with medications. While quitting smoking is always a good option, it is essential to inform your healthcare professional if you are taking medication and are considering quitting. Cigarette smoke can interact with some medications, so quitting smoking may also have an impact. In some cases, a dosage adjustment of your medication may be necessary.

Natural health products

Although they are available over the counter, natural health products can be dangerous with other drugs. Many products can interact with prescription or non-prescription drugs. For example, St. John's wort can cancel the effect of birth control pills, and omega-3s can increase the risk of bleeding when combined with anticoagulants. The best person to consult is your pharmacist to ensure that a natural product is compatible with your medication.

Over-the-counter medications

Again, just because they're over-the-counter doesn't mean that medications available without a prescription at your pharmacy can't interact with your prescriptions. Think of decongestants that can increase blood pressure, anti-inflammatories that can irritate the stomach and thin the blood, or cough suppressants that can interact with antidepressants. It is necessary to talk to your pharmacist to ensure that the chosen product is appropriate for your situation.

Consult your pharmacist

If you would like to make an appointment with your pharmacist to discuss your medications, some Familiprix-affiliated pharmacies offer online appointment scheduling for this service. If you cannot find a time slot, do not hesitate to contact your pharmacy directly. Remember, your pharmacist is THE drug specialist and the most accessible front-line healthcare professional!

The drugs and pharmaceutical services featured on the website are offered by pharmacists who own the affiliated pharmacies at Familiprix. The information contained on the site is for informational purposes only and does not in any way replace the advice and advice of your pharmacist or any other health professional. Always consult a health professional before taking or discontinuing medication or making any other decision. Familiprix inc. and the proprietary pharmacists affiliated with Familiprix do not engage in any way by making this information available on this website.