I think there are only a few people on here who have used Tysabri, but for those who did, I am wondering what the response time was? Dave123 -- you said several weeks. Do you mean after the second infusion? 3 weeks? hspencer, how quickly did you respond? Jid -- have you had any sign of response yet? Just curious because I am two weeks into it. Sometimes I think it's helping a litle and sometimes I feel the same. Last night and the night before I had a horrid pain (different from my regular one) but now that's gone. Since I've been off antibiotics (Cipro 1000/mg day) my temp has gone back up to over 100 at times. But daytimes I still feel better. It's very strange. Anyway, I am just wondering what the experience from others has been on the time to feel a solid response.