However, patients with diabetes reported that while sildenafil is effective, it is less so than reported by other patients. Sildenafil treatment is well tolerated by patients. Its main side effects are headache, flushing, nasal congestion, dyspepsia, and visual disturbances. All of these seem to be dose-related. There have been a few reports of priapism, which demands immediate attention so that penile damage does not occur.
Few patients discontinue sildenafil due to adverse reactions.
Sildenafil is contraindicated in patients taking nitrates in any form or patients with a known hypersensitivity to any components in the tablet. There have been deaths associated with sildenafil usage and these seem to be caused by concomitant use of nitrates with sildenafil. However, some feel it may be due to preexisting cardiovascular risk or associated with the physical activity of having sex. The American College of Cardiology and the American Heart Association have listed some recommendations regarding the use of sildenafil. Patients with congestive heart failure and borderline low blood pressure and borderline low volume status.