A 57-year-old male presents after accidentally firing his son’s expired epinephrine autoinjector containing 0.3 mg of epinephrine into his left thumb two hours prior to arrival. He endorses mild pain and numbness at the tip of his thumb. The patient had spoken to poison control who had instructed him to present to the Emergency Department if his symptoms did not improve after two hours. He denied any palpitations or other systemic symptoms.
Extremities: Pallor noted at the distal tip of his left thumb extending 2 to 3 cm proximally with a central 2 mm area of bruising. Capillary refill could not be elicited in the left thumb pad. Sensation was intact to light touch and motor strength was intact in the left thumb.
Treatment modalities are primarily based on case reports and range from conservative measures to local infiltration of vasodilatory medications.  Conservative treatments include digital massage, warm water soaks, and local application of nitroglycerin paste. Varying degrees of success have been associated with these conservative treatments. In our case, conservative measures failed and we proceed with local infiltration of phentolamine mesylate. The dosage and volume administered vary widely in reports; however, commonly reported doses were 2 to 3.5 mg of phentolamine reconstituted with 1 to 2 ml of 2% lidocaine or normal saline. This is then injected locally at multiple locations in the affected region or as a digital block. In our case, reperfusion occurred within minutes after local infiltration with approximately 1.5 mg of phentolamine reconstituted with lidocaine. No systemic side effects were noted.
There have been no documented reports of ischemic necrosis associated with accidental digital epinephrine injection. Additionally, spontaneous resolution in the majority of cases at less than two hours has been widely reported, though in some cases symptoms may persist for hours to days. [1,2] Though phentolamine may provide rapid symptomatic relief of pallor, pain, and/or paresthesia for the patient, limited data exist on long-term clinical outcomes and the overall effect on prognosis. 
The recommendation to never use lidocaine with epinephrine for digital nerve blocks or local digital infiltration is propagated in medical education. However, a large retrospective review of 127 accidental digital epinephrine injection cases noted a majority had spontaneous resolution.  Further, large studies from surgical literature have reported that local infiltration of lidocaine with epinephrine is safe and resulted in prolonged anesthesia and reduced bleeding.
Spontaneous resolution of accidental digital epinephrine injection often occurs within two hours and no cases of ischemic necrosis have been reported.
Symptomatic relief may be achieved with local phentolamine mesylate infiltration if conservative measures have failed. Commonly reported total effective doses range from 2 to 3.5 mg in volumes of 1 to 2 ml of 2% lidocaine or normal saline.
McNeil C, Copeland J. Accidental digital epinephrine injection: to treat or not to treat? Can Fam Physician. 2014 Aug;60(8):726-8. PMID: 25122817; PMCID: PMC4131962.
Muck AE, Bebarta VS, Borys DJ, Morgan DL. Six years of epinephrine digital injections: absence of significant local or systemic effects. Ann Emerg Med. 2010 Sep;56(3):270-4. doi: 10.1016/j.annemergmed.2010.02.019. Epub 2010 Mar 26. PMID: 20346537.