Xeloda (Capecitabine) interacts with warfarin, phenytoin, and other drugs. Learn which medications, supplements, and foods to avoid during treatment.
If you're taking Xeloda (Capecitabine), it's critical to know what other medications, supplements, and even foods can interact with it. Some interactions can make Xeloda less effective. Others can be dangerous — even life-threatening.
This guide covers the most important Xeloda drug interactions, what to avoid, and what to tell your doctor before starting treatment.
Xeloda is a prodrug that converts to 5-fluorouracil (5-FU) in your body. Along the way, it affects — and is affected by — several enzymes and biological pathways. When another medication uses the same pathways, the result can be:
Because Xeloda is a chemotherapy medication with a narrow safety margin, even moderate interactions can have serious consequences. For background on how Xeloda works in your body, see our mechanism of action guide.
This is the most important drug interaction for Xeloda. Capecitabine significantly increases the blood-thinning effect of warfarin, which can lead to dangerous bleeding — including internal bleeding. This interaction carries a boxed warning on Xeloda's label.
If you take warfarin while on Xeloda:
Tell your doctor immediately if you're taking warfarin or any other blood thinner.
Capecitabine can increase blood levels of Phenytoin, a seizure medication. Higher Phenytoin levels can cause toxicity symptoms including dizziness, confusion, and difficulty walking. Your doctor will need to monitor Phenytoin levels and may adjust your dose.
Leucovorin enhances the toxicity of 5-FU (and therefore Xeloda). While this combination is sometimes used intentionally in certain cancer regimens, it can increase the risk of severe side effects including diarrhea, mouth sores, and myelosuppression. Your oncologist will account for this if prescribing both.
These antiviral drugs inhibit the DPD enzyme, which your body needs to safely break down 5-FU. Taking Sorivudine or Brivudine with Xeloda can cause fatal toxicity. This combination is absolutely contraindicated. You must wait at least 4 weeks after stopping these antivirals before starting Xeloda.
Allopurinol, commonly used for gout, may reduce the effectiveness of Capecitabine. If you take Allopurinol, tell your oncologist so they can evaluate whether an alternative gout medication might be appropriate during your Xeloda treatment.
Xeloda can lower your blood cell counts. Taking it with other drugs that suppress bone marrow — including many other chemotherapy agents — increases the risk of severe neutropenia (low white blood cells), thrombocytopenia (low platelets), and anemia. Your oncologist will monitor your blood counts closely if you're on combination therapy.
Capecitabine may inhibit the CYP2C9 liver enzyme. Drugs metabolized by CYP2C9 — including some NSAIDs, certain diabetes medications, and others — may have increased blood levels when taken with Xeloda. Inform your doctor about all medications you take.
Folic acid (similar to leucovorin) can enhance 5-FU toxicity. While routine multivitamins with small amounts of folic acid are generally fine, high-dose folic acid supplements should be discussed with your oncologist.
Antacids containing aluminum or magnesium hydroxide may slightly increase Capecitabine absorption. While this isn't usually clinically significant, mention any antacid use to your doctor.
Avoid live vaccines during Xeloda treatment. Because Xeloda suppresses your immune system, live vaccines (like the nasal flu spray, shingles vaccine Zostavax, or MMR) could cause serious infections. Inactivated vaccines (like the flu shot) are generally safe and recommended.
Xeloda should be taken within 30 minutes after a meal. This isn't just a suggestion — food affects how the drug is absorbed and helps reduce nausea. For more on dosing, see our Xeloda uses and dosage guide.
There are no specific food contraindications with Xeloda, but staying well hydrated is essential — especially if you're experiencing diarrhea, which is a common side effect. Dehydration can worsen kidney function, and since Xeloda is cleared through the kidneys, this can increase drug toxicity.
While there's no direct pharmacological interaction between Capecitabine and alcohol, drinking alcohol during chemotherapy is generally discouraged. Alcohol can worsen nausea, dehydration, and liver stress — all of which can compound Xeloda's side effects.
Before your first dose, make sure your oncologist knows about:
Bring a complete medication list — including dosages — to every oncology appointment. Many dangerous interactions can be avoided simply by keeping your care team fully informed.
Xeloda is a powerful cancer-fighting medication, but it requires careful coordination with your other medications. The warfarin interaction alone can be life-threatening if not properly monitored.
The simplest thing you can do to stay safe: tell your doctor everything you take — prescription, OTC, supplements, vitamins, all of it. And if any other doctor or dentist prescribes something new while you're on Xeloda, check with your oncologist first.
For more information about Xeloda, explore our guides on uses and dosage, side effects, and how to save money. If you need help finding Xeloda at a pharmacy, Medfinder can help you check availability near you.
You focus on staying healthy. We'll handle the rest.
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