Hard flaccid syndrome
Hard flaccid syndrome
Hard flaccid syndrome (HFS) is a rare condition where the penis stays firm and semi-rigid even when not aroused. It may feel hard to the touch, look shrunken or rubbery, and can be painful or uncomfortable. People with HFS might also have erectile difficulties, unusual penis sensations, urinary changes, pelvic floor tension, or unusual penis shapes.
Most cases start after an injury to the penis or pelvis, or after nerve problems in the lower spine. In some people, no clear cause is found.
What causes it? The main idea is that the sympathetic nervous system is overly active in the penis after an injury, causing the smooth muscle to stay contracted. Treatments that have been used include alpha blockers and PDE5 inhibitors, but there is limited evidence they help. Injections of phentolamine into the penis can briefly relax the tissue.
Diagnosis: There is no standard test for HFS. Many people self-diagnose, and doctors usually rule out other conditions. There is no proven cure.
Where the problem can start (five possible areas): the penis itself; the pelvic nerves; nerves in the lower spine (cauda equina); the spinal cord; or the brain. The penis is the most common trigger.
Research and outlook: HFS is not well understood, and more study is needed to improve diagnosis and treatment.
This page was last edited on 2 February 2026, at 06:00 (CET).