Claritin improves my physical pois symptoms by about 50%. I'm not sure about cognitive symptoms. I take the generic version of claritin, called Loratadine, from the brand, equate. I take one 10mg tablet about an hour before ejaculation. I think claritin only works if taken before "o". It's been working for at least 4 months now I think - I'll have to check my notes on that. Edit- It's actually been working for more than 5 months now.
Saw Palmetto also reduces my physical symptoms, but to a lesser extent. Maybe by about 15%. I used to get pain during urination and bowel movements during pois and saw palmetto solved that for the most part, but it also reduces my joint pain and other physical pois. I take one Swanson brand 540mg capsule about 15min before orgasm. Edit- This has also been working for more than 5 months.
As far as the other members who use these I know GoingCrazy recently found claritin to work for him and there are at least 3 others who use antihistamines, but I'll have to look around a bit to find their posts. Animus still uses saw palmetto even though he is already cured.
I'll get to Niacin later.