• Diabetes
• Heart disease
• Clogged arteries (atherosclerosis)
• Prior surgeries
• Low testosterone (hypogonadism)
• Cancer
• Psychological conditions such as depression
• Medications
• Some over-the-counter medications and herbal supplements
• Heavy alcohol use
• Too much caffeine
• Tobacco use
• Poor diabetes control
• Damage to pelvic nerves caused by prolonged pressure from a narrow bicycle seat
• Illicit drugs such as marijuana, MDMA (Ecstasy) and heroin
• Use of narcotic pain medications such as codeine