I've taken lofepramine (very old but effective tricyclic anti-depressant) for phobic anxiety for nearly 22 years - without it I overthink, get panicky and anxious and my fears stop me getting on with life. As long as I take it, my phobia is there in the background and peeps out occasionally, but is well-controlled.
It has also, however, brought me 22 years of migraine. 
So I take medication for that as well! I'm sure it's the lofepramine - I first took it for 4 months in about 1992, and I recall having a couple of horribly debilitating headaches (something I hardly ever suffered from) which did not recur after I stopped the medication. They only returned when I started it again in 1999.
I briefly tried sertraline in about 2007 but the side effects - mainly night sweats and absence of libido - were so bad, I returned to the trusty lofepramine.
I don't know what's worse - the headaches stopping me from doing everything I want, or the phobia stopping me from functioning normally!
I expect the GP will suggest citalopram if I ask for a change. What's that like for anxiety, as opposed to depression? Has anyone switched to it after years and years on something else?