Pyzchiva Drug Interactions: What to Avoid and What to Tell Your Doctor

Before starting Pyzchiva (ustekinumab-ttwe), it is important to tell your doctor and pharmacist about all medications, supplements, and vaccines you are currently taking or plan to receive. While Pyzchiva has a relatively manageable drug interaction profile compared to some other biologics, there are specific categories of interactions that require careful monitoring.

Interaction Category 1: Live Vaccines — Avoid While on Pyzchiva

This is the most important interaction to understand. Pyzchiva suppresses parts of your immune system, which means live vaccines can potentially cause serious problems while you are being treated.

Live vaccines to avoid while taking Pyzchiva include:

• MMR (measles, mumps, rubella)
• Varicella (chickenpox)
• Yellow Fever
• Live attenuated nasal influenza vaccine (FluMist)
• BCG vaccine: Do not receive BCG for at least one year before starting Pyzchiva and for at least one year after stopping it

Inactivated (non-live) vaccines such as the regular flu shot, Tdap, shingles vaccine (Shingrix is a recombinant vaccine — not live), and COVID-19 vaccines can be given while on Pyzchiva, though they may not be as effective as in people with a fully intact immune system.

Interaction Category 2: CYP450 Enzyme Substrates — Monitor Closely

Chronic inflammation can suppress the activity of liver enzymes called CYP450 enzymes, which are responsible for metabolizing many medications. When Pyzchiva reduces inflammation, it can normalize CYP450 activity — which means drugs that were previously metabolized slowly (due to suppressed CYP450 activity in an inflamed patient) may now be metabolized more quickly. This can lower blood levels of certain medications.

Medications that require monitoring if taken concurrently with Pyzchiva include:

• Warfarin (Coumadin): A blood thinner. Pyzchiva may alter warfarin's effectiveness. Your doctor should monitor your INR closely when starting, stopping, or changing your Pyzchiva dose.
• Cyclosporine: An immunosuppressant used in organ transplant patients and for some autoimmune conditions. Drug levels should be monitored when used with Pyzchiva.
• Other narrow therapeutic index drugs metabolized by CYP2C9, CYP2C19, CYP3A4, CYP2D6, or CYP1A2 pathways

Note: In clinical studies of ustekinumab in patients with Crohn's disease, no clinically significant changes were observed in the exposure of caffeine, warfarin, omeprazole, dextromethorphan, or midazolam. However, for safety, monitoring is still recommended — especially at treatment initiation.

Interaction Category 3: Other Immunosuppressants

Pyzchiva is sometimes used in combination with immunomodulators like methotrexate (MTX), azathioprine (AZA), or 6-mercaptopurine (6-MP) in Crohn's disease and ulcerative colitis. Clinical pharmacokinetic analyses have shown that Pyzchiva clearance is not significantly affected by these medications — meaning they can generally be used together under physician supervision.

Similarly, NSAIDs and corticosteroids do not appear to significantly alter Pyzchiva's pharmacokinetics. However, combining multiple immunosuppressants always warrants careful monitoring for increased infection risk.

Interaction Category 4: Allergen Immunotherapy

Pyzchiva has not been evaluated in patients undergoing allergen immunotherapy (allergy shots). Ustekinumab products may decrease the protective effect of allergen immunotherapy by reducing tolerance, potentially increasing the risk of an allergic reaction. Use caution if you are currently receiving or have recently received allergen immunotherapy, and discuss this with both your prescriber and your allergist.

What to Tell Your Doctor Before Starting Pyzchiva

Before your first Pyzchiva dose, tell your doctor about:

• All prescription and over-the-counter medications you take
• All vitamins, supplements, and herbal products
• Any vaccines you have recently received or plan to receive
• Any history of tuberculosis, active infections, or recent exposure to TB
• Any history of cancer or malignancy
• If you are pregnant, planning to become pregnant, or breastfeeding
• If anyone in your household needs a live vaccine — since live virus can spread to immunocompromised people

Pregnancy and Breastfeeding

Pyzchiva may pass into breast milk in small amounts. Animal studies have not shown harmful effects in offspring, and observational data in pregnant women have not identified a clear association with major birth defects. However, it is preferable to use effective contraception during Pyzchiva treatment and for at least 15 weeks after the last dose. Discuss the risks and benefits with your doctor if you are pregnant or planning to become pregnant. For more on side effects and safety, see our guide: Pyzchiva Side Effects. And to find Pyzchiva at a pharmacy near you, visit medfinder.