It should not be used in anyone allergic to any of the components used to make sildenafil tablets. Also, as discussed above, the use of multiple phosphodiesterase inhibitors at the same time, is not recommended. It has not been studied.
The use of Sildenafil is not recommended in patients with Pulmonary Veno-Occlusive Disease (PVOD).
ABSOLUTELY no one should take sildenafil if they “are currently on nitrate/nitrite therapy.” That includes even if the patient uses of nitrates/nitrite therapy intermittently. Also, no one who uses recreational nitrates/nitrites (poppers, etc.) should use sildenafil.
Geriatric (The Elderly), Hepatic (Liver) Disease, Renal (Kidney) Impairment
Sildenafil is metabolized by a complex system that can be compromised in the elderly, or in patients who suffer from liver disease, or in those whose kidney function is reduced by illness or age. Therefore, it is recommended “not to exceed a maximum single dose of 25 mg sildenafil in a 48 hour period.”
Moreover, certain drugs have a dramatic effect on the metabolism of sildenafil similarly increasing the blood level dramatically. Therefore, those taking erythromycin, itraconazole, ketoconazole, saquinavir, and ritonavir should follow the same regimen.
Angina (Chest Pain), Aortic Stenosis, Cardiac Arrhythmias (Irregular Heartbeats), Cardiac Disease (Heart Disease), Coronary Artery Disease (Narrowing of the Heart Arteries), Heart Failure, Hypertension (High Blood Pressure), Hypotension (Low Blood Pressure), IHSS (Idiopathic Hypertrophic Subaortic Stenosis–a Heart Defect), Myocardial Infarction (Heart Attack), Stroke (like a heart attack but affecting the brain)
“There is a degree of cardiac risk associated with sexual activity; therefore, prescribers, should evaluate the cardiovascular status of their patients prior to initiating any treatment for erectile dysfunction.” [NOTE: This means that if you and your provider have a reason to believe after diagnosing erectile dysfunction that you are not healthy enough for sex, you shouldn’t use anything that will help you have sex until you are healthier. Your doctor counts on an honest answer about your health and your capacity to be sexually active. It may seem overly cautious but think about it; if you aren’t healthy enough for sex, shouldn’t you take care of your health before trying to regain your sex life? There have been more than 75 deaths due to cardiac events “reported in association with sildenafil use.” It may not seem like many deaths but you don’t want to be the person who bumps that number over 100.]
The PDR advises that “caution should be used if sildenafil is prescribed in the following groups: patients who have suffered a myocardial infarct, stroke, or life threatening arrhythmias in the last 6 months; patients with resting hypotension (BP<90/50) or resting hypertension (BP>170/100); patients with fluid depletion; patients with cardiac disease, heart failure, or coronary artery disease which causes unstable angina.”
The PDR notes that the American College of Cardiology recommends that sildenafil be used in caution with patients (not on nitrates, of course) with active coronary ischemia, meaning they have blocked heart arteries that is compromising the function of their heart, such as would show by having symptoms like chest pain or by failing a stress test. They also advise caution in anyone with low blood pressure or low blood volume or in anyone with high blood pressure on a “complicated, multidrug, antihypertensive program.” Patients with “Left Ventricular Outflow Obstruction (e.g., aortic stenosis, idiopathic hypertrophic subaortic stenosis)” should be approached with caution as they, and patients with poor control of the swings in their blood pressure, can be very sensitive to sildenafil and other vasodilators (drugs that open up the blood vessels). They also recommend that doses of sildenafil over 25 mg not be given within 4 hours of taking an alpha-blocker (e.g. doxazosin).
Leukemia, Multiple Myeloma, Penile Structural Abnormality, Polycythemia, Priapism, Sickle Cell Disease
Priapism is an erection lasting more than 4 hours and it can occur with the use of sildenafil. Priapism can be painful but, with or without pain, an erection that lasts over 4 hours could result in damage to the tissues of the penis. People with the above conditions are at greater risk of suffering from priapism with the use of sildenafil. The PDR states, “sildenafil and other agents for the treatment of erectile dysfunction, should be used with caution in patients with penile structural abnormality (such as angulation, cavernosal fibrosis, or Peyronie’s disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell disease, leukemia, multiple myeloma, polycythemia, or history of priapism).”
Human Immunodeficiency Virus (HIV) Infection
The PDR states, “Patients should be reminded that sildenafil, when used for erectile dysfunction, offers no protection against sexually transmitted disease.”
Coagulopathy (Bleeding Abnormalities), Peptic Ulcer Disease (Stomach Ulcer)
There is no safety information yet accumulated on how sildenafil affects patients with bleeding disorders or active stomach ulcers so caution is recommended.
Gastroesophageal Reflux Disease (GERD–heartburn due to reflux of acid), Hiatal Hernia (part of stomach slips upward through the diaphragm)
Sildenafil decreases the pressure of the valve that stops acid from coming back up from the stomach and into the esophagus. It also inhibits the movement of the esophagus itself. It could make symptoms worse for people with GERD or a hiatal hernia so it is recommended that it be used with caution in these patients.
Non-arteritic Anterior Ischemic Optic Neuropathy (NAION), Retinitis Pigmentosa, Visual Disturbance
The PDR states, “Use sildenafil cautiously in patients with preexisting visual disturbance. Post-marketing reports of sudden vision loss have occurred with phosphodiesterase inhibitors. Vision loss is attributed to a condition known as non-arteritic anterior ischemic optic neuropathy (NAION), where blood flow is blocked to the optic nerve. Patients with a history of NAION are at increased risk for recurrence. Only use a PDE5 inhibitor in these individuals if the anticipated benefit outweighs the risk.” It is never recommended for patients with known hereditary degenerative retinal disorders, including retinitis pigmentosa.
There are other situations that would give a healthcare provider pause. Some would be if you have lightheadedness, fainting spells, leg cramping when you walk, inability to climb stairs or walk a few blocks without getting short of breath, or if you have allergies to any of the other phosphodiesterases or their components. These, and any other symptoms, must be discussed.
A Special Warning for Pilots and Air Traffic Controllers
Some people experience visual side effects when taking PDE5 inhibitors for erectile dysfunction. Due to the sensitive nature of their work, pilots and air traffic controllers should not take Viagra or sildenafil within 6 hours of aviation related duties. Cialis (tadalafil) is a much longer acting medication. Pilots and air traffic controllers should not take Cialis within 36 hours of aviation related duties. Daily Cialis use, at any dose, is not an option for men with these professions.