You should take sildenafil 30 to 60 mins before planned sexual activity on an empty stomach (high-fat meal may delay the absorption of sildenafil and slow down its effect).
If you are taking nitrate-containing medications (e.g. GTN, isosorbide mononitrate), please let our doctors know. After taking sildenafil, please ensure the safety interval (minimum 24 hours) has elapsed before taking nitrate-containing medications. Taking nitrate-containing medications within the safety interval can cause a dangerous fall in your blood pressure.
Also, same as everything we try for the first time, you have to watch for an allergy reaction after taking sildenafil, despite its rare occurrence. If you experience itchy skin rashes, swollen eyes/lips/face/tongue, and shortness of breath, please head to the nearest emergency service or call 995 immediately.