Priapism - prolonged involuntary erection - is an adverse effect with some drugs. Here is a list of the more commonly reported:

• Androgens
• Anticoagulants
• Antihypertensives: Hydralazaine, labetolol, phentolamine, prazosin
• Antipsychotics
• Cantharidin
• Cocaine
• Diazepam
• Marijuana
• Sildenafil
• Trazadone
• Yohimbine