John,
I was in the Phase III trial for Avonex around 1995 and was treated with it, after it was approved in the US, for about ten years. I never thought it was great and I eventually got needle fatigue. I switched to Tysabri and was treated with it for seven years, until my titer score got too high. I think it slowed my progression. After a short time on Aubagio I moved to Lemtrada. I’m now about 2 1/2 years post Round 2 of that treatment. I definitely feel it’s slowed my progression and think it’s improved some symptoms slightly (bladder & bowel, primarily).
I never had any real side effects with any of these DMTs, though I do remember my BP being checked during every Tysabri infusion. A low BP might account for the dizziness. Have you discussed it with your neuro?
Ed