Hi,
Sorry for the delay. Yes, you have a choice to accept or reject the invitation. You can also go back and remove a friend if it turns out it was a mistake to add them by using your Friends tab in My MedHelp.
MedHelp
You don't have to accept or decline any invitation in a hurry. If you aren't comfortable with them, decline. If you just don't know them very well, but have interaction, than you might want to send them an email, thanking them, but saying that you would like to get to know them better.
You get a choice. If someone adds you as a friend, you will see "you have 1 invitation" written on the top right hand corner of your screen. You have the choice to either accept or reject their invitation.