Found this and it did the trick for me! Thanks for your answers above though
if (saved == true)
{
lblsuccess.Visible = true;
lblsuccess.Text = "Visit saved";
ClientScript.RegisterStartupScript(this.GetType(), "HideLabel", "<script type=\"text/javascript\">setTimeout(\"document.getElementById('" + lblsuccess.ClientID + "').style.display='none'\",2000)</script>");
}