Hypertensive urgency: an important aetiology of rebound hypertension.

A 46-year-old African-American man with a history of hypertension, end-stage kidney disease (on haemodialysis) and previous cocaine misuse presented to the emergency room with a sudden onset of severe headache and diaphoresis without other neurological or cardiovascular signs/symptoms. He checked his blood pressure at home and found it to be 230/130. It did not improve despite taking two serial doses of oral clonidine 0.3 mg. Evaluation with head CT and lumbar puncture demonstrated no acute intracranial process, such as subarachnoid haemorrhage. These symptoms started after he took Libido-Max, an over-the-counter supplement for erectile dysfunction. This supplement includes yohimbine, an α-2 antagonist, which counteracts the effects of oral clonidine, one of his routine antihypertensive medications. This led to rebound hypertension and made his hypertensive urgency resistant to oral clonidine. He was successfully treated with intravenous labetalol and his symptoms quickly resolved after lowering of his blood pressure.