 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  put extra strain on your heart, especially if you have heart problems. If you have heart problems and experience any of these serious side effects while having sex, stop and get medical help right away: severe dizziness, fainting, chest/jaw/left arm pain, nausea. Rarely, sudden decreased vision, including permanent blindness, in one or both eyes (NAION) may occur. If this serious problem occurs, stop taking sildenafil and get medical help right away. You have a slightly greater chance of developing NAION if you have heart disease, diabetes, high cholesterol, certain other eye problems ("crowded disk"), high blood pressure, if you are over 50, or if you smoke. Rarely, a sudden decrease or loss of hearing, sometimes with ringing in the ears and dizziness, may occur. Stop taking sildenafil and get medical help right away if these effects occur. In the rare event you have a painful or prolonged erection lasting 4 or more hours, stop using this drug and get medical help right away, or permanent problems could occur. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, </s>