What the FDA labels say about taking them together
Clonidine and phentolamine
Clonidine's FDA label of March 30, 2026 names phentolamine in its warnings section; the phentolamine labels PlainMeds reads (2) do not name clonidine.
Check it at the source: the clonidine FDA label on DailyMed (effective March 30, 2026, Unichem Pharmaceuticals (USA), Inc.); the phentolamine FDA label on DailyMed (effective March 15, 2026, Oyster Point Pharma, Inc.).
What does the clonidine label say about phentolamine?
Clonidine label, warningsAn excessive rise in blood pressure following discontinuation of clonidine hydrochloride tablets therapy can be reversed by administration of oral clonidine hydrochloride or by intravenous phentolamine.
Javadin label (Azurity Pharmaceuticals, Inc., October 24, 2025), warnings and precautionsIf rebound hypertension occurs, reverse hypertensive crisis with oral clonidine or IV phentolamine.
Source: FDA drug label (Javadin, NDA220256), Azurity Pharmaceuticals, Inc., effective October 24, 2025 (SPL set c36d94f5-a30d-4997-b141-e79a4ea45ecf), via openFDA
Source: FDA drug label (clonidine hydrochloride), Unichem Pharmaceuticals (USA), Inc., effective March 30, 2026 (SPL set 21bfa28f-20df-43fd-bb80-b720d3b40696), via openFDA; the full label on DailyMed
What does the phentolamine label say about clonidine?
Phentolamine's label (effective March 15, 2026) and its 1 other brand-application label do not name clonidine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Ryzumvi), NDA217064 (Famygen Life Sci), as published by Oyster Point Pharma, Inc., effective March 15, 2026 (SPL set 96bb1e53-c2cc-4e60-a21a-db0269c371bf), 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
| Clonidine | Phentolamine | |
|---|---|---|
| Labeled for | High blood pressure, ADHD, Pain | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0241 per tablet 0.1 mg tablet | 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