Nonaneurysmal subarachnoid hemorrhage after udenafil intake.

We report a 67-year-old man who presented with severe headache after taking 50 mg of udenafil, a new phosphodiesterase 5 inhibitor. Computed tomographic imaging of the brain revealed a small amount of acute subarachnoid hemorrhage localized around basal cisterns (anterior to midbrain and pons). There were no aneurysms in the cerebral arteries, although vein of Galen stenosis was suspected after magnetic resonance venography. This case anecdotally suggests that phosphodiesterase 5 inhibition might trigger perimesencephalic subarachnoid hemorrhage with venous hypertension possibly associated with vein of Galen stenosis.