It really does depend on a multitude of things, Your body, being fit, overweight, what you have had to eat, do you have a cold, your age and other underlying health conditions. I get the 100mg tabs and cut them in half. They normally work well but I do find they are better on an empty stomach or a light snack but I avoid things like a full english, having alcohol has also had an effect so I avoid that now. I think you will need to try 50 mg a few times and see how you get on. I am fit and healthy but still get red flushes, headaches, blurred vision and a stuffy nose. Ive heard people say they take aspirin for the headache and a nasal spray to clear the blocked nose. I would get a doctors advice as every individual will react differently, personally I just persevere with the side affects as I find it bad enough taking the one medication without taking others to combat the side affects, where do you stop?
It can also depend on your desire or urge, although the meds are working and you have increased blood flow, do you actually have the urge if she a munter and not doing anything for you? Some people black out with them, Im normally knackered after a punt and tend to fall asleep on the train or bus home, I wouldnt drive as no doubt Id fall asleep and crash!!