What the FDA labels say about taking them together
Aprepitant and fosaprepitant
Aprepitant's FDA label of July 5, 2024 names fosaprepitant in its contraindications section, and fosaprepitant's label names aprepitant too. The aprepitant label: “Some substrates of CYP3A4 are contraindicated with EMEND.”
Check it at the source: the aprepitant FDA label on DailyMed (effective July 5, 2024, Merck Sharp & Dohme LLC); the fosaprepitant FDA label on DailyMed (effective July 29, 2026, AVYXA Pharma, LLC).
What does the aprepitant label say about fosaprepitant?
Aprepitant label, contraindicationsCONTRAINDICATIONS EMEND is contraindicated in patients: who are hypersensitive to any component of the product.
Aprepitant label, drug interactionsSome substrates of CYP3A4 are contraindicated with EMEND [see Contraindications (4) ].
Aprepitant label, warnings and precautionsSee Full Prescribing Information for recommendations regarding contraindications, risk of adverse reactions, and dosage adjustments of EMEND and concomitant drugs. ( 4 , 5.1 , 7.1 , 7.2 ) Warfarin (a CYP2C9 substrate):
Source: FDA drug label (EMEND), NDA021549 (Msd), as published by Merck Sharp & Dohme LLC, effective July 5, 2024 (SPL set 696f9e80-9cae-403b-de9e-078343ce4713), via openFDA; the full label on DailyMed
What does the fosaprepitant label say about aprepitant?
Fosaprepitant label, contraindicationsInhibition of CYP3A4 by aprepitant, the active moiety, could result in elevated plasma concentrations of this drug, which is a CYP3A4 substrate, potentially causing serious or life-threatening reactions, such as QT prolongation, a known adverse reaction of pimozide [see Warnings and Precautions (5.1) ].
Fosaprepitant label, drug interactionsSingle dose fosaprepitant does not induce CYP3A4. Aprepitant is a substrate, an inhibitor, and an inducer of CYP3A4.
Fosaprepitant label, warnings and precautionsWARNINGS AND PRECAUTIONS CYP3A4 Interactions: Fosaprepitant is a weak inhibitor of CYP3A4, and aprepitant, the active moiety, is a substrate, inhibitor, and inducer of CYP3A4; see Full Prescribing Information for recommendations regarding contraindications, risk of adverse reactions, and dosage adjustment of NAVITRUX and concomitant drugs. ( 4 , 5.1 , 7.1 , 7.2 ) Hypersensitivity Reactions (including anaphylaxis and anaphylactic shock): May occur during or soon after infusion. If symptoms occur, discontinue the drug.
Source: FDA drug label (NAVITRUX), AVYXA Pharma, LLC, effective July 29, 2026 (SPL set a41b7c3a-1376-43a7-b5b9-6ba2eba1e169), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Aprepitant | Fosaprepitant | |
|---|---|---|
| Labeled for | Nausea and vomiting | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $46.42 per capsule 40 mg capsule | n/a |
| Shortage now | A presentation being discontinued | A presentation being discontinued |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once