Eriacta 100 mg contains sildenafil 100 mg, and dizziness is a recognized side effect of sildenafil. D DailyMed +1 Why it can cause dizziness Sildenafil relaxes blood vessels. This can produce a temporary drop in blood pressure, which may make you feel light-headed, dizzy, weak, or unsteady—particularly when standing up. With 100 mg, this effect can be noticeable in some people. D DailyMed +1 Dizziness is more likely if you: Already have low blood pressure. Take blood-pressure medicines or alpha-blockers. Are dehydrated or haven't eaten/drunk adequately. Drink significant amounts of alcohol. Take other medicines that lower blood pressure. D DailyMed +1 For reference, dizziness was reported in about 2% of patients in clinical trials of sildenafil used for ED. D DailyMed Important: Do not take sildenafil with nitrates such as nitroglycerin, because blood pressure can fall dangerously. D DailyMed If your dizziness is severe, you faint, have chest pain, or develop sudden vision/hearing loss, seek urgent medical attention. D DailyMed If you tell me how long after taking Eriacta 100 mg the dizziness starts and how long it lasts, I can explain whether the timing fits a sildenafil side effect.