What the label lists and what reports show
Phentolamine side effects
Phentolamine's FDA label: “The most common adverse reactions that have been reported are instillation site discomfort (16%), conjunctival hyperemia (12%), and dysgeusia (6%).” FAERS holds 158 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is ocular hyperaemia (20 reports).
- Generic listed
Check it at the source: the phentolamine FDA label on DailyMed (effective March 15, 2026, Oyster Point Pharma, Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most common adverse reactions that have been reported are instillation site discomfort (16%), conjunctival hyperemia (12%), and dysgeusia (6%).
Table 1: Adverse Reactions with Frequency Greater Than or Equal to 3% and Equal to or Exceeding Control
This table is printed in the Oraverse label published by Septodont, Inc. of December 5, 2018; the label quoted above does not print one.
| Reaction | 0.2 mg (N = 83) N (%) | 0.4 mg (N = 284) N (%) | 0.8 mg (N = 51) N (%) | Total (N = 418) N (%) | Total (N = 359) N (%) |
|---|---|---|---|---|---|
| Patients with AEs | 15 (18) | 82 (29) | 20 (39) | 117 (28) | 96 (27) |
| Tachycardia | 0 (0) | 17 (6) | 2 (4) | 19 (5) | 20 (6) |
| Bradycardia | 0 (0) | 5 (2) | 2 (4) | 7 (2) | 1 (0.3) |
| Injection site pain | 5 (6) | 15 (5) | 2 (4) | 22 (5) | 14 (4) |
| Post procedural pain | 3 (4) | 17 (6) | 5 (10) | 25 (6) | 23 (6) |
| Headache | 0 (0) | 10 (4) | 3 (6) | 13 (3) | 14 (4) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe most common adverse reactions that have been reported are instillation site discomfort (16%), conjunctival hyperemia (12%), and dysgeusia (6%). ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Viatris at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. RYZUMVI was evaluated in 642 subjects in clinical trials across various subject populations. The most common ocular adverse reactions reported in > 5% of subjects were instillation site discomfort including pain, stinging, and burning (16%) and conjunctival hyperemia (12%). The only non-ocular adverse reaction reported in > 5% of subjects was dysgeusia (6%).
Source: FDA drug label, 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
What do FAERS reports show?
158 reports list phentolamine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 11 are coded as a death and 44 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 23 reactions below, 2 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Phentolamine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions