Which symptoms it improved by how much, how many you take how long before orgasm?
Percentage-wise, I think most symptoms are improved by 50-70%
My symptoms include depression, anxiety, losing interest in doing things, muscle weakness, itching (especially thighs and lower arms), stuttering, frequent urination/defecation, lower appetite, etc.
I would say antihistamines work slightly better in improving my emotional symptoms than the physical ones (including stuttering).
I take them roughly an hour before orgasm.
By the way, I took Claritin in the past and have been taking Zyrtec in the last two years. For me, Claritin takes too much time to reach its greatest efficacy, and more importantly, if I take it on a daily basis, I cough (with no phlegm) and my throat feels itchy. I now take two 10mg Zyrtec every day.