Can I ask why your Dr made the change? Was it his idea, or did you feel like you needed it?
We don't know what fillers they use in these meds. I would ask my pharmacist.
Do the pills look the same, or did your pharmacy switch companies? I get one of my medications at 2 different pharmacies. They're the exact same medication and the exact same dose but they look completely different at one pharmacy. And one pill is bigger than the other so I know it has more fillers in it.
So, I am thinking it's the fillers in your meds or the increase is causing your symptoms. Talk to both your Dr and your pharmacist. Ask if you can get a read out of what's in your medication. If it contains no animal products then you may have to go back down to 150 mgs to see if that helps.
I really hope you get this figured out soon. If you can go to the pharmacy today to see about getting a read out that would be great. Ask while you're there if you can take Benadryl to help with the hives until you can see your Dr.
It's certainly possible, but almost every human is allergic to dairy and it doesn't generally manifest itself in hives -- it's usually digestive problems and, long-term, immune system problems. With eggs, the problem could be sulphur, and there could be sulphur in your new supplement -- it's a common allergen and more likely to cause hives, but my guess is, you've eaten a lot of eggs in you life and a lot of dairy and never gotten hives from it. It's just common sense that if you add something new in your life and you get something new that bothers you, it's probably the new thing. Also realize you're taking a lower dose now than you were before -- you were taking 300mg a day and now you're taking 225mg. That can cause a withdrawal problem, as Effexor is one of the most difficult meds to stop taking and has to be done carefully. Hives, though, aren't a withdrawal symptom, and the mg difference might not be as great as it sounds -- extended release pills often mean expensive toilet water, though that's less common with pharmaceuticals than with vitamins or supplements. That's because the pill goes to your digestive system and from there to your bloodstream, but it's always possible before the pill is finished releasing slowly its contents you will evacuate it. But my guess is, Remar has answered your question -- you're on a generic, and there are several companies that make generics. Sometimes they don't have the same quality as the brand name so you get less in your system, and sometimes different companies use different additives. The easiest way to tell is to either try the same med from a different generic manufacturer, or to go back on your old med; if in either case the hives go away and don't come back you'll know what the problem was, and you already know from your own history eggs and dairy don't give you hives.