Assalamu alaikum, for some reason i dont knwo i cannot reply to you guys, it wont work, so i am going to copy paste the Q & A and the reply here:
Question Number:280436:Question:Assalamu alaikum, about 2-3 months ago i was home alone, and my brother is married, he lives with us so does his wife, they have their own room, but its like 99 percent of the time always open when they arent here also its open some times when they are, we live together, so i was home alone, and im pretty sure the door was opened as it awlays is usually, i was just looking at the medicines for my brother also his wife's are there, then i realiazed wat i was doing is wrong, so i asked Allah Subhanawata`la for for forgiveness, and did not do it again. Now i think i have to tell my brother that i looked at the medications, or is it fine and i dont have to since i asked for forgiveness? I mean its not that i found out anything new, like i already know wat my brother takes but ofcourse wat i did was wrong. Jazak Allah KhairReply:Can you make us clear what is your actual concern? What did you do wrong? Did you enter without permission or something else?
My reply:What my concern is that there was no one home, and i am almost certain that the door was probably open because it is 99 percent of the time, so i was home alone, i was looking at the medicines for my brother and his wife, then i realized wat i was doing is wrong so i repented to Allah subhanawata`la, now my concern is do i have to tell my brother what i did? its not like i found out anything, we live together and are close, so i already know what my brother takes and so.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

What is understood from your question is that your entering in the room of your brother and his wife and looking at the medicine might have upset your brother, if the matter is so, then you were mistaken. You have to repent to Allaah and should not repeat this act. In principle, you have to ask pardon from your brother and his wife, but if you believe that informing them of what you did may cause a greater harm then you should not inform them rather you should ask forgiveness in general and supplicate for them.

Allaah Knows best.