What the FDA labels say about taking them together
Dihydroergotamine and letermovir
Letermovir's FDA label of January 14, 2026 names dihydroergotamine in its contraindications section; the dihydroergotamine labels PlainMeds reads (4) do not name letermovir. The letermovir label: “Co-administration is contraindicated due to risk of ergotism.”
Check it at the source: the dihydroergotamine FDA label on DailyMed (effective March 6, 2025, Oceanside Pharmaceuticals); the letermovir FDA label on DailyMed (effective January 14, 2026, Merck Sharp & Dohme LLC).
What does the dihydroergotamine label say about letermovir?
Dihydroergotamine's label (effective March 6, 2025) and its 3 other brand-application labels do not name letermovir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Dihydroergotamine Mesylate), NDA020148 (Bausch), as published by Oceanside Pharmaceuticals, effective March 6, 2025 (SPL set 977de209-c53a-4cb4-9f3f-1e850600a9dc), via openFDA; the full label on DailyMed
What does the letermovir label say about dihydroergotamine?
Letermovir label, contraindicationsErgot alkaloids: Concomitant administration of PREVYMIS in patients receiving ergot alkaloids may result in increased concentrations of ergot alkaloids (ergotamine and dihydroergotamine) due to inhibition of CYP3A by letermovir, which may lead to ergotism [see Warnings and Precautions (5.1) and Drug Interactions (7.2 , 7.3) ].
Letermovir label, drug interactionsConcomitant Drug Class and/or Clearance Pathway/Drug Name: ergotamine, dihydroergotamine; Effect on Concentration ↓ =decrease, ↑ =increase: ↑ ergotamine, dihydroergotamine; Clinical Comments: Co-administration is contraindicated due to risk of ergotism [see ].
Source: FDA drug label (PREVYMIS), Merck Sharp & Dohme LLC, effective January 14, 2026 (SPL set 1b49df80-be4f-47e0-a0b7-123f3e69395b), 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
| Dihydroergotamine | Letermovir | |
|---|---|---|
| Labeled for | Migraine | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $29.44 per mL 4 mg/mL nasal spray | n/a |
| Shortage now | No current entry | No current entry |
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