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Phentolamine Side Effects

Medically reviewed by Drugs.com. Last updated on Apr 6, 2023.

Applies to phentolamine: injection powder for solution.

Serious side effects of Phentolamine

Along with its needed effects, phentolamine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking phentolamine:

Rare

Other side effects of Phentolamine

Some side effects of phentolamine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common or rare

Phentolamine injected into the penis may cause tingling at the tip of the penis. This is no cause for concern.

For Healthcare Professionals

Applies to phentolamine: compounding powder, injectable powder for injection, injectable solution.

Cardiovascular

Cardiovascular side effects have included hypotension due to reduced peripheral vascular resistance. This has been a significant cardiovascular complication of phentolamine therapy in some cases. Acute and prolonged hypotensive episodes with reflex tachycardia and cardiac arrhythmias have been reported. Overdosage has been characterized primarily by cardiac arrhythmias, tachycardia and severe hypotension or shock.[Ref]

If severe hypotension develops, prompt elevation of the patient's legs, infusion of IV fluids and/or volume expanders, and, if necessary, an infusion of norepinephrine (titrated to an acceptable blood pressure) is recommended. Epinephrine should not be used since it may cause a paradoxical reduction in BP.

While limited data have shown that phentolamine can attenuate the marked increases in pulmonary artery pressure and vascular resistance associated with exercise in some patients with primary pulmonary hypertension (PPH), its role in this disease is not clear. A single case of severe, worsened pulmonary hypertension has been reported after the administration of phentolamine to a young woman with PPH. Theoretically, the drug was expected to cause pulmonary arterial vasodilation and an improvement of her condition. Apparently, in patients with PPH, the pulmonary vessels become progressively unresponsive to vasodilator therapy. Phentolamine did induce decreased systemic peripheral vascular resistance in this case, which was associated with increased cardiac output, increased pulmonary blood flow, and, because of a constant pulmonary vascular resistance, increased pulmonary artery blood pressure.[Ref]

Nervous system

Nervous system side effects have included weakness and dizziness. Anxiety, headache, pupillary contraction and visual disturbances are signs of toxicity.[Ref]

Respiratory

Respiratory system side effects have included nasal stuffiness, probably due to peripheral vasodilation.[Ref]

Gastrointestinal

Gastrointestinal side effects have included nausea, vomiting, and diarrhea.[Ref]

Genitourinary

Genitourinary side effects among male patients who directly inject the penile cavernous body have included prolonged erections/priapism, fibrous plaque formation, severe local pain, cavernositis, urethritis, ecchymosis with hematoma, gross hematuria, and hematospermia. Urinary incompetence has not been reported, although the drug has been used to successfully treat urinary obstruction due to benign prostatic hypertrophy.[Ref]

Hepatic

Hepatic side effects have included transient hepatic abnormalities, manifested as elevations in liver function tests, with direct injection of phentolamine and papaverine in 0.4% to 40% of men with erectile impotence.[Ref]

Metabolic

Metabolic side effects have included hypoglycemia. This was probably due to stimulation of insulin as a result of alpha-adrenergic blockade.[Ref]

References

1. Romankiewicz JA. Pharmacology and clinical use of drugs in hypertensive emergencies. Am J Hosp Pharm. 1977;34:185-93.

2. Gould L, Reddy CV, Gomprecht RF. The effect of phentolamine on conduction in the bundle of His. Angiology. 1975;26:507-10.

3. Cohen ML, Kronzon I. Adverse hemodynamic effects of phentolamine in primary pulmonary hypertension. Ann Intern Med. 1981;95:591-2.

4. Se Do Cha, Kirschbaum M, Maranhao V, Paine E, Gooch AS. Phentolamine for primary pulmonary hypertension. Ann Intern Med. 1979;91:927-8.

5. Ruskin JN, Hutter AM Jr. Primary pulmonary hypertension treated with oral phentolamine. Ann Intern Med. 1979;90:772-4.

6. Van Way CW 3d, Faraci RP, Cleveland HC, Foster JF, Scott HW Jr. Hemorrhagic necrosis of pheochromocytoma associated with phentolamine administration. Ann Surg. 1976;184:26-30.

7. Gould L, Reddy CV, Oh KC, Kim SG, Becker W. The effect of phentolamine on intra-Hisian conduction. J Electrocardiol. 1978;11:391-4.

8. Zentgraf M, Baccouche M, Junemann KP. Diagnosis and therapy of erectile dysfunction using papaverine and phentolamine. Urol Int. 1988;43:65-75.

9. Suzuki T, Mori C, Asakage H, Akaza H, Kawabe K, Ueno A, Koiso K, Niijima T. Pheochromocytoma with remission following phentolamine-induced shock. Urology. 1984;23:582-4.

10. Diagnostic and Therapeutic Technology Assissment (DATTA). Vasoactive intracavernous pharmacotherapy for impotence: papaverine and phentolamime. JAMA. 1990;264:752-4.

11. Product Information. Regitine (phentolamine). Ciba-Geigy Pharmaceuticals. 2001;PROD.

12. Hauptman JB, Modlinger RS, Ertel NH. Pheochromocytoma resistant to alpha-adrenergic blockade. Arch Intern Med. 1983;143:2321-3.

13. Kiruluta HG, Andrews K. Urinary incontinence secondary to drugs. Urology. 1983;22:88-90.

14. Caine M, Pfau A, Perlberg S. The use of alpha-adrenergic blockers in benign prostatic obstruction. Br J Urol. 1976;48:255-63.

15. Watters GR, Keogh EJ, Carati CJ, Earle CM, Wisniewski ZS, Tulloch AG, Lord DJ. Prolonged erections following intracorporeal injection of medications to overcome impotence. Br J Urol. 1988;62:173-5.

16. Kerfoot WW, Carson CC. Pharmacologically induced erections among geriatric men. J Urol. 1991;146:1022-4.

17. Fouda A, Hassouna M, Beddoe E, Kalogeropoulos D, Binik YM, Elhilali MM. Priapism: an avoidable complication of pharmacologically induced erection. J Urol. 1989;142:995-7.

18. Levine SB, Althof SE, Turner LA, Risen CB, Bodner DR, Kursh ED, Resnick MI. Side effects of self-administration of intracavernous papaverine and phentolamine for the treatment of impotence. J Urol. 1989;141:54-7.

19. Larsen EH, Gasser TC, Bruskewitz RC. Fibrosis of corpus cavernosum after intracavernous injection of phentolamine/papaverine. J Urol. 1987;137:292-3.

20. Moriel EZ, Rajfer J. Sodium bicarbonate alleviates penile pain induced by intracavernous injections for erectile dysfunction. J Urol. 1993;149:1299-300.

21. Kursh ED, Bodner DR, Resnick MI, Althof SE, Turner L, Risen C, Levine SB. Injection therapy for impotence. Urol Clin North Am. 1988;15:625-9.

22. Sidi AA. Vasoactive intracavernous pharmacotherapy. Urol Clin North Am. 1988;15:95-101.

23. Fernandez JA, Basha MA, Wilson GC. Emergency treatment of papaverine priapism. J Emerg Med. 1987;5:289-91.

24. Althof SE, Turner LA, Levine SB, Risen CB, Bodner D, Kursh ED, Resnick MI. Sexual, psychological, and marital impact of self-injection of papaverine and phentolamine: a long-term prospective study. J Sex Marital Ther. 1991;17:101-12.

25. Bodner DR, Leffler B, Frost F. The role of intracavernous injection of vasoactive medications for the restoration of erection in spinal cord injured males: a three year follow up. Paraplegia. 1992;30:118-20.

26. Wyndaele JJ, de Meyer JM, de Sy WA, Claessens H. Intracavernous injection of vasoactive drugs, an alternative for treating impotence in spinal cord injury patients. Paraplegia. 1986;24:271-5.

27. Stief CG, Gall H, Scherb W, Bahren W. Mid-term results of autoinjection therapy for erectile dysfunction. Urology. 1988;31:483-5.

28. Persson I, Larsen L. Serum insulin concentration after alpha-adrenergic blockade and secretin in diabetics. Acta Endocrinol (Copenh). 1972;71:331-7.

29. Linde J, Deckert T. Increase of insulin concentration in maturity-onset diabetics by phentolamine (Regitine) infusion. Horm Metab Res. 1973;5:391-5.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

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