I have discovered that taking anti-histamines has had a positive effect on my DP/DR. I take Claritin and Zantac. I have also had results from Zyrtec.
I had an allergy test done both the blood and prick test, which basically showed no allergies. I don't believe my DP is allergy related.
To my surprise I was talking with another member of this forum who has suffered from long term DP and they said they have been taking Claritin to help with DP for forever. I couldn't believe someone else with DP had similar results.
By no means has this been a cure. I'd say at best it has made me feel 15% up to possibly 30% better. More like 15%. I don't know about you, but I'll take 15% anyday.
I'm not claiming it's a cure, but it's something cheap and over the counter you could try. If you're interested, I would recommend trying Claritin and just getting the lowest amount you can to try out.
If you notice any results please report back here and let us know!