When should i take venlift? Side effect?

Should i take venlift when i am experiencing anxiety?i mostly get anxious before studying.i was advised venlift for 2 weeks in the morning but i usually dont study in the morning. I was adviced 37.5 mg venlift in morning and 25 mg prothiaden at night,but my doc told me to gradually leave prothiaden after 15days. Now since my subscription expired,and also i want a second opinion, i 2wanted to know if i should take only venlift(as i stopped prothiaden) 37.5 mg or 75 in the evening or in the morning. Is taking 37.5 mg sufficient to help me study without anxiety.Do i have to take it at a regular time everyday or can i take it only before i start studying any time of the day?after taking prothiaden i often experienced headache which rendered me unable to study, so if that happens with venlift also, is there any way to reverse or lessen the side effect?