Filitra 20 mg contains vardenafil, a PDE5 inhibitor used to treat erectile dysfunction (ED). Like other medicines in this class, it is generally safe when prescribed, but there are important warning signs that should never be ignored. Serious warning signs (seek urgent medical help) Stop using the medicine and get emergency care if you experience: Chest pain, pressure, or tightness during or after ***** activity Severe dizziness or fainting (possible dangerous drop in blood pressure) Sudden vision loss in one or both eyes Sudden hearing loss or ringing in ears Erection lasting more than 4 hours (priapism) — can cause permanent damage if untreated Signs of allergic reaction such as rash, swelling of face/lips, or difficulty breathing   Important caution signs (medical advice needed) These symptoms suggest the drug may not be suitable or the dose may be too strong: Persistent headache or flushing Severe indigestion or nausea Unusual heart palpitations Marked drop in blood pressure symptoms (lightheadedness when standing) Dangerous interactions warning Filitra 20 mg must never be taken with nitrates (used for chest pain/angina), such as nitroglycerin, because it can cause a life-threatening fall in blood pressure. Caution is also needed with some alpha-blockers and blood pressure medicines.