18 yr old w/chronic but controlled high bld press. on bystolic! was listening 2 coroided arteries w/stethoscope &heard slight "bruit"- left side. bad?

FMD: In an 18 year old and hypertensive, is there any cause found for his hypertension? I would be concerned about having fmd fibromuscular dysplasia. Or carotid dissection. Although carotid bruit have a weak association with significant carotid disease . Check with his/her doctor asap to check renal and carotid arteries duplex ultrasound or mra.

No not bad: See your doctor. A bruit in an 18 yo is decidedly uncommon. Your doctor can tell you if it's real or a normal sound.