Fildena Chewable 100 mg contains sildenafil, so the same cardiovascular precautions that apply to sildenafil/Viagra apply to it. People should not take it without medical clearance if they have had certain recent or serious heart problems, particularly: Heart attack (myocardial infarction) within the last 6 months Stroke within the last 6 months Life-threatening or serious abnormal heart rhythm within the last 6 months Unstable angina (unpredictable or worsening chest pain) Severe heart failure Very low blood pressure (below about 90/50 mmHg) or severely uncontrolled high blood pressure (>170/110 mmHg). The reason is that sildenafil widens blood vessels and can lower blood pressure, while ***** activity itself places additional stress on the cardiovascular system. Most important interaction Never use sildenafil with nitrate medicines such as nitroglycerin or isosorbide, which are commonly used for angina. The combination can cause a potentially dangerous drop in blood pressure. Also, 100 mg is a relatively high sildenafil dose. If someone has a history of heart disease, it's better to have a doctor determine whether sildenafil is appropriate and what dose is safest.