8 months ago i switched from humira - which stopped working - to Enbrel. At first I didn't think it was working and it took a couple of weeks for me to figure out how long to leave the blasted injection out so it would burn like crazy when I injected. With that said I feel better over all than I did when I was on Humira, so no complaints there - but I am not saying I'm "good as new" or pain free... just better. And sometimes "better" is a huge step in the right direction. :) What I have noticed in the last few months are HEADACHES. not just regular take to advil and keep going headaches. I am talking - I think my head my explode headaches - that last for days sometimes. I have noticed an up tick in the number and fequency of my headaches. Not all are killers but most are mind numbing and really painful. I know from researching side effects of enbrel that headaches are common but this is just crazy. I mean I LOVE being able to walk and use my hands and have a lower level of pain in my body but the trade off seems to be these unbelievable headaches. I am no weenie either so for me to crawl into bed because of a stupid headache means something. I have also stated to notice that my face is breaking out. I some how made it through my teen years without having to experience any blemishs and break outs. Now that I am in my mid 30's I find it distrubing and frustrating to have break outs! I am not sure if I can blame Enbrel for this as well but I am starting to think it might be the culprit as non of the rest of my medications have changed and its the only "new" one in the past year. In addition I am also not sleeping well as when i was on Hurmia. I wake up tried (and stiff and achey - but with RA who doesn't?) and have to fight off falling asleep before lunch! And last but not least, I have been trying to lose weight since January and its the middle of may and have managed to drop 6lbs despite eating less and walking. I am almost convinced that enbrel has some kind of magic pull to fat! LOL! I go for walks and because of enbrel I have been able to do two 5K walks (after which I hurt so bad I couldn't move for the next 2 days), but without it I never would have been able to attempt to walk a 5K. I still have daily pain that if asked I'd rate low because its become apart of my daily life now and accept it as "normal". Its funny how with RA one's defination of low or normal for pain changes. My family members tell me they forget I have RA because I don't look like I am in pain or that I don't talk about it. Well just because I am not screaming OUCH OUCH OUCH doesn't mean I don't hurt and just because I am not bent over in the fetal position doesn't mean I am not in pain. I love them but I have serious doubts that they "get it" when it comes to RA...and i don't expect them to, after all its not happening to them.
So I love Enbrel and what it has allowed me to be able to do - it has truely given me so much more of my life back to me that RA pain took away; but at the same time I HATE HATE HATE enbrel for the all the ugly unpleasant side effects it brings to my life.
Is entirely possible that your headaches are caused by Enbrel, but it's also entirely possible that that's time goes on, your body will get used to the drug in the headaches will subside. I am very sensitive to medication and always start on about half the dose of what other people do, so you may want to talk to your doctor about the option of reducing the dose and letting your body get used to things more slowly, then increasing again. Of course, you have to balance the pros and cons of possibly reducing the headaches with the smaller impact of a smaller dose of Enbrel, but maybe your doctor can bridge the gap with some prednisone to give Enbrel a bit of a boost until it really kicks in. At some point, you may also want to talk to your doctor about combination therapy - it's quite common for one medication not to do the trick on its own, but to do better with some help from one of the other of the DMARDs (disease modifying antirheumatic drugs like the Biologics, methotrexate, Plaquenil, etc.)
It's also possible that your headaches are sinus headaches - as you've already been on Humira, you're probably very aware of the sinus-related side effects, but different medications work differently and in my experience, Enbrel packs more of a punch on your sinuses then Humira does. Check out my post on managing side effects for tips on how to keep things down to a dull roar in your sinuses. Have you gotten your blood pressure checked recently? If my blood pressure is up, I often get a headache, so you may want to look into that.
I would in general suggest that you talk to your rheumie about the headaches - your doctor should be aware of any funky symptoms.
Good luck! And congratulations on the 5Ks!