Nitroglycerin Transdermal Patch and Dihydroergotamine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Nitroglycerin Transdermal Patch
Dihydroergotamine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Dihydroergotamine toxicity (peripheral ischemia, paresthesias, nausea, vomiting)
Interaction Deep Dive
The concurrent use of oral nitroglycerin and dihydroergotamine has been shown to increase the dihydroergotamine area under the concentration time curve by greater than 50%, when compared to dihydroergotamine given alone. In some cases the use of dihydroergotamine has precipitated angina in patients maintained on nitroglycerin1.
Why it happens (mechanism)
Decreased dihydroergotamine metabolism
Common questions
Can I take Nitroglycerin Transdermal Patch and Dihydroergotamine together?
Dihydroergotamine toxicity (peripheral ischemia, paresthesias, nausea, vomiting) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Nitroglycerin Transdermal Patch and Dihydroergotamine interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Nitroglycerin Transdermal Patch or Dihydroergotamine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Bobik A, Jennings G, Skews H, et al: Low oral bioavailability of dihydroergotamine and first-pass extraction in patients with orthostatic hypotension. Clin Pharmacol Ther 1981; 30:673-679. PubMed
Keep reading about Nitroglycerin Transdermal Patch
Keep reading about Dihydroergotamine
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