ED is erectile dysfunction. You basically get a permanent softie while you're on it. Happens to about 40% of men who use [I think] either one. For me it sort of destroys my libido too. Also seems to give me an I don't really care about anything sort of feeling. You have to decide whether the benefits of the drug are worth the possible side effects. The best thing is to try one of them first and see if it helps. If not try the other one. If you're feeling amorous you can always back off for a few days and then start up again. For that you will need a good supply of 25mg or more sizes. I take 75mg of PreGabalin 3X per day so I'd need some 50mg and 25mg capsules. They should be covered by insurance since they are different sizes.