Hi Nas,
If I was to try the antihistamine method myself, I would do it in two phases:
I would first take loratadine 10mg daily for 5 to 7 days, and refrain from O during that period, and then, still taking a loratadine every day, have 2x25 benadryl at time of O, and go on with this for 2 to 3 weeks, having the time to test for 2 or 3 releases and noting the results each time, in term of % of relief and duration of symptoms. Taking loratadin 10mg daily fora few weeks is quite safe, some people have to take this every day year round for non-seasonal allergies, but anyone has to check if it is safe for himself before doing so.
If I had unsatisfactory results with this, I would go for a second phase of testing, and would repeat the same protocol, but changing the loratadine with cetirizine, taking Reactine daily for 2 to 3 weeks, and benadryl, at time of O, and taking notes on the results, for one O a week, and compared with the previous phase results, and see what is the most effective.
In one month from now, you will have done most of this testing,
I would also have no more than 2 releases in the same week, and preferably only one per week, because I view any relief methods as limited, so better test any method with a relatively low frequency of ejaculation, unless I feel any method could become "overwhelmed" by the cumulative POIS triggering, and the data obtained are not conclusive ( a method could have been efficient if not for 3 ejaculations in 5 days, for example, but you never been able to see it)
As you see, I strongly believe that a rigorous, "scientific" testing is required in order to get anywhere when testing any relief method for POIS. You do not have to actually put a white coat on, though, to do so ;-) It only takes time, patience and a structured approach in order to find an efficient method. I think it's better taking time to really goes through a method, not overlooking a potential benefit, unless this method causes you clear side effects or disadvantage or worsening of POIS, so then you clearly have to stop to test it. After methodical testing, and no significant results, then you will know that you have thoroughly tested that method and that it is not effective for your type of POIS. You then can test another method ( so many have been suggested on the forum so far, and the main ones are listed in my POIS types chart),
In my own case, I had to find things by myself ( I found this forum 2 years ago and have POIS for 38 years...), It took me years only to find that magnesium and green tea extract were giving me relief. Once I have found this forum, it took me 5 to 6 months of intensive testing in order to come up with my current pre-pack. So be patient, have a "POIS relief testing" notebook or file on your laptop where you note everything you test for further reference, and be patient, and you will find eventually something that will bring you some relief. I would be surprised that after 6 months of structured tests, you would have not find at least a 50% relief whne lowering your frequency to about once a week.
Be sure to include in your overall method some healthy changes to your diet, it has been beneficial for many POIS sufferers.