I was going to say to numb with an ice cube. Alex. Already got there first ;) so I second her post.
Barb
You can try either cold or hot packs on the area. Sometimes drugs do this when your body is getting used to them and it goes away. I have not heard of Rebif always stinging. My Copaxone did for 15 minutes. I gave it when I was watching a TV show I liked to distract myself. Your mind can't focus on two things at once.
Alex
Hi there, I used Rebif for a year and my memory isn't what it should but I remember occasional stinging.
If you aren't already I would recommend taking some acetaminophen about 45 minutes before the injection. That may help the sting and curb any potential side effects.
I don't remember too much sting once I got used to the max dose.
Also, make sure your injection site is clean and dry and that you are using a site with enough skin.
The Rebif nurse had told me the alcohol wipes weren't necessary but if you do use them give the area a few minutes to dry first.
Any lotion, alcohol, etc. will promote stinging.
Good luck,
Corrie