If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher. If you experience any prolonged effects, bring it up with your doctor. Do not be discouraged if your doctor does not give you a prescription. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily. If you sense that this is the case, it might be best to ask for a referral to another doctor or a specialist. Your doctor will tell you not to take sildenafil if you are taking street drugs containing nitrates.If you have these symptoms, stop taking VIAGRA and contact a doctor right away. have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure. have had heart surgery within the last 6 months. have pulmonary hypertension. have had a stroke. Tips for talking to your doctor about ED. If you’ve been having difficulty getting or sustaining erections, talk about it with your doctor. Such a conversation is never easy, . Talking to Your Doctor About Erectile Dysfunction. 1. Create a List of Your Concerns. You need to have a plan when consulting your doctor for a specific case. The key to a productive visit is to set 2. Consult First a Primary Care Doctor. 3. Bringing Up .