Key takeaways
- Kisqali (ribociclib) is broken down by the CYP3A4 enzyme, so drugs or foods that affect this enzyme can change Kisqali levels in your blood. This can make the drug less effective or increase your risk of serious side effects.
- Major interactions to avoid include St. John’s wort, grapefruit products, and certain antibiotics, antifungals, and antiseizure medications. Some drugs like tamoxifen and ondansetron (Zofran) should be avoided because they significantly raise the risk of dangerous heart rhythm problems.
- Talk with your healthcare professional about all medications, supplements, and health conditions before starting Kisqali. Pre-existing liver disease, kidney disease, heart conditions, or electrolyte imbalances may require dose adjustments or extra monitoring.
Kisqali (ribociclib) is a targeted therapy prescribed to treat HR-positive, HER2-negative breast cancer. A wide range of drugs, foods, and supplements can interact with Kisqali, significantly altering the level of this medication in your system and increasing your risk of serious side effects.
This article explains which substances to avoid, when dose adjustments are needed, and what you can do to help prevent dangerous interactions.
Kisqali’s interactions are primarily due to how it’s processed in the body and its effects on other drugs. The CYP3A4 enzyme breaks down Kisqali in your body. Any drug or substance that affects this enzyme can change Kisqali levels, impacting its effectiveness and side effect risk.
Kisqali is also a moderate inhibitor of the CYP3A enzyme, which means it can increase levels of other drugs that are broken down in the same way. Kisqali can prolong the QTcF interval (a measure of heart rhythm), especially when combined with other QT-prolonging drugs. This can increase the risk of serious heart rhythm problems.
The following chart shows common drug interactions with Kisqali, but this is not an exhaustive list. Talk with your doctor and pharmacist about all prescription and over-the-counter (OTC) drugs you take before starting Kisqali.
| Drug class | Common examples | Interaction results |
|---|---|---|
| antipsychotics | • aripiprazole (Abilify, Aristada, others) • brexpiprazole (Rexulti) • haloperidol (Haldol) • risperidone (Risperdal, Uzedy, others) | can increase the risk of long QT syndrome |
| arrhythmia drugs | • amiodarone (Nexterone, Pacerone) • procainamide • sotalol (Betapace, Sotilyze, others) | high risk: Can cause dangerous heart rhythm changes |
| certain antibiotics | • ciprofloxacin (Cipro) • clarithromycin • rifampin (Rifadin, Rifamycin) | may increase Kisqali side effects or make Kisqali less effective (rifampin) |
| certain antidepressants | • citalopram (Celexa) • sertraline (Zoloft) • trazodone • venlafaxine (Effexor XR) | increases risk of heart rhythm issues (long QT syndrome) |
| certain antiemetics (nausea medication) | • ondansetron (Zofran) | increases risk of heart rhythm problems; doctors usually avoid this combination |
| certain antifungals | • itraconazole (Sporanox, Tolsura) • ketoconazole • voriconazole (Vfend) | significantly raises Kisqali levels in the blood |
| certain antiseizure medications | • carbamazepine (Carbatrol, Equestro, others) • phenytoin (Dilantin, Phenytek) | can make Kisqali less effective at treating cancer |
| certain antivirals | • nelfinavir (Viracept) • ritonavir (Norvir) | raises risk of Kisqali toxicity |
| certain benzodiazepines | • alprazolam (Xanax, Xanax XR) • clonazepam (Klonopin) • diazepam (Valium) • midazolam (Seizalam) | Kisqali raises the levels of these drugs, increasing sedation and side effects |
Note: You should also avoid taking Kisqali with tamoxifen, as clinical trials have shown that this combination poses a much higher risk of serious heart rhythm issues compared with other treatments.
You should not take St. John’s wort during treatment with Kisqali. This herb speeds up Kisqali’s breakdown so much that the drug may stop working against the cancer.
While there are no known interactions between Kisqali and vitamins, it’s important to check with your doctor or pharmacist because certain multivitamins contain herbal blends that could interfere with your Kisqali treatment.
Certain medical conditions or other health factors can increase your risk of interactions with Kisqali. Before starting treatment with this medication, talk with your doctor about your health history.
Tell your doctor if any of the following conditions apply to you:
- Liver or kidney disease: You may require a lower Kisqali starting dose to help your body process the medication safely.
- Heart conditions: Pre-existing issues such as heart failure or a history of heart attack can increase your risk of dangerous heart rhythm changes during Kisqali treatment.
- Electrolyte imbalances: Low levels of potassium, calcium, or magnesium in your blood must be managed before you start Kisqali in order to protect your heart.
- Pregnancy and breastfeeding: Kisqali can cause significant harm to a developing fetus or a nursing infant, requiring strict use of effective birth control during treatment and for 3 weeks after your last dose.
You should avoid grapefruit, grapefruit juice, pomegranate products, and Seville oranges (often found in marmalades) while taking Kisqali. These foods can block the enzymes that break down Kisqali, leading to dangerously high levels of the drug in your body.
Yes. There are no known interactions between acetaminophen (Tylenol) and Kisqali. It’s generally considered safe for pain or fever relief, but always confirm with your oncologist.
Yes, you can take proton pump inhibitors (PPIs), H2 blockers, and antacids with Kisqali. These do not interfere with how Kisqali is absorbed.
There is no direct interaction between Kisqali and alcohol, but caution is advised. Both substances are processed by your liver. Heavy drinking can increase the risk of liver toxicity and may worsen Kisqali side effects such as headache and fatigue.
Learn more about a few of the interactions that can occur with Kisqali.
Anxiety and sleep medication
Kisqali acts as a block for the enzyme that clears benzodiazepines such as Xanax or Valium from your system. If you take Kisqali in combination with one of these drugs, the sedative effects may last a lot longer or be a lot stronger than intended. Your doctor may need to lower your dose of these medications.
Cannabis and CBD
Marijuana and CBD products can interact with Kisqali. They may compete for the same liver enzymes, potentially increasing the side effects of the cannabis or affecting how Kisqali works. Always be open with your care team if you use these products.
Heart rhythm (long QT syndrome)
One of the most serious risks with Kisqali is the prolongation of the QT interval. This risk is compounded if you take other drugs that do the same, such as:
- antidepressants: particularly citalopram (Celexa) and sertraline (Zoloft)
- antiemetics: Ondansetron is a common trigger for this interaction. Your doctor may suggest other anti-nausea meds such as prochlorperazine (Compazine).
- antipsychotics: haloperidol (Haldol), aripiprazole (Abilify), risperidone (Risperdal)
Apart from taking Kisqali exactly as prescribed, there are a few other things you can do during treatment to help prevent interactions. These include:
- Creating a
list of all medications you take, including prescription and OTC drugs, as well as any vitamins, supplements, and herbs you use. - Scanning your medication’s label and paperwork for “CYP3A4” warnings and looking for a grapefruit sticker on the bottle. Both are major red flags for a Kisqali interaction.
- Filling all of your prescriptions at the same pharmacy so their system can automatically flag potential interactions.
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