Hi, ! I am sorry you are experiencing some new issues with heat and sun sensitivity. Ocrevus does not list heat or sun sensitivity as potential side effects, but I have learned that when it comes to medications, almost anything is possible. Have you started any other new medications or even supplements that may be behind the sun sensitivity? Also, general heat sensitivity is a pretty common MS symptom, so that could be just a new symptom of your MS. I can't hazard a guess, as I am not your doctor.
If you haven't done so already, I would definitely talk to your doctor about this. And frankly, I bet you know more about dealing with the heat than most of us! Arizona summers are on a whole other level! That said, we have lots of information on beating the heat and I will share some of the articles with you. Here's one -- https://multiplesclerosis.net/living-with-ms/time-year-staying-cool. And here's another one -- https://multiplesclerosis.net/living-with-ms/heat-sensitivity. And one more -- https://multiplesclerosis.net/living-with-ms/summer-heat-intolerance. You may consider looking into a cooling vest, if you don't already have one. A cooling vest can help you stay cool if you have to be out and about in the heat.
Now, sun sensitivity is an issue I haven't seen discussed much within this community. But, I am a big proponent of protecting one's skin. You can find some great sun hats with SPF 50+ online or even places like Costco. They range in price and style widely. I personally wear my sun hat anytime I am out in the summer sun for more than a few minutes. There are also lots of clothes with SPF protection, too. The best ones tend to not be natural fibers, but they are so lightweight and comfortable and I find them easy to wear.
I hope some of these tips help! Stay cool! I sure don't envy Arizona summers, but I get a little envious of your weather when I'm dealing with the cold dreary days of late winter!
Best, Erin, MultipleSclerosis.net Team Member.