I'm taking 200mg dermerol for bad migraine but isn't working can i take one more that would be 300 mg?

You can, but: it won't help. There are much better medications to abort migraine than Demerol (meperidine hydrochloride). Migraine is a serious and complex neurologic disorder. Today effective management of migraine involves three specific strategies: 1) patient education 2) non-pharmacological management (diet, sleep hygiene, acupuncture) and 3) pharmacological (triptans, topamax, etc) management. Rec.:see orofacial pain specialist.