Is it safe to drink alcohol while taking valacyclovir for oral herpes?

Yes, in moderation. There are no contraindications to drinking alcohol while taking valacyclovir for oral herpes. Contraindications/cautions include: hypersens to drug/class/compon, caution if immunocompormised, advanced hiv, renal impairment, concurrent nephrotoxic agents, elderly, if dehydrated. Getting drunk may not be safe to yourself and/or to others, however. That's why i suggest drinking in "moderation".
No. You should not have alcohol when treating oral heroes with the medication. It interfere with the effect of the medication.