I had ocular megraines and transient feelings of derealisation when I was a teenager before my dp started.
After my dp started - age 19 - I seemed to have an almost perpetual headache. I found that my ability to handle toxins such as cigarettes and alcohol was much reduced - more hangovers, worse hangovers. I found that my ability to handle other illnesses like colds and flu was also much reduced - I felt much more ill than pre-dp. I likened my dp to an extreme form of the detachment I used to feel as a child when I had flu or a bug.
After my dp started I started to get many more megraines, much more severe than before.
I get ocular megraines (revolving prism/circular saw expanding to fill my field of vision together with blindspots of nothingness and heightened dp/dr) and when the ocular phase ends I get a blinding headache but my dp seems to vanish temporarily whilst I have the headache. Sometimes I feel very sick but have never actually been sick.
My megraines are often brought on by common triggers - stress, lack of sleep, over exertion, red wine, port, yeasty beer (real ale), alcohol generally, cheese, chocolate, milk, eggs, sometimes caffeine if drinking a lot of coffee when tired. I am much more susceptible to these triggers than I was before my dp.
Sometimes I think that my dp/dr is a permanent low level megraine - a seizure that has been arrested in its tracks but not eliminated.
Whilst taking Lamotrigine over a couple of years I did not experience a single megraine.
I now avoid all of the above triggers most of the time and drink alcohol only in strict moderation (apart from the odd night out which I always regret. I rarely get megraines and avoidance reduces my dp/dr.
I understand that Propranalol, a beta blocker, is prescribed for daily consumption and is effective in preventing megraine attacks. I was advised not to take this with klonopin for fear of lowering my blood pressure too much - but it is something I will try again in the future.
In recent times when I have had a cluster of ocular megraines I have found that drinking about two pints of water as soon as the visual disturbance starts will actually stop a megraine or at least delay its onset. This has worked for me on 5 out of 5 occasions I have tried it - but you have to glug that water down to dilute whatever it is in your stomach that is upsetting your head.
There is a connection between megraine and dp/dr which has been written about several times before on this board - but I suspect that the relationship is both complex and ill-understood. But there are clues here and I for one would be interested to know how many people were megraine sufferers before they got dp/dr - might put up a poll on this question.