@ZipLine-- I'm not a doctor but I've spoken to several different doctors and pharmacists about this and the consensus was that it's okay to take lysine in moderation during pregnancy.
Lysine is not a medication, it's an amino acid. You can't take anti-viral medications during pregnancy but you can take a moderate dose of lysine when you feel a breakout coming. So try not to take it all the time. As far as I know, the cream is safer than the oral supplements because you will use less and less of the medication will enter the bloodstream.
I highly recommend doing your own research on this and you should ask your doctor before you take anything.